Release Notes for Debian 10 (buster), 64-bit ARM --------------------------------------------------------------------- The Debian Documentation Project (https://www.debian.org/doc/) This document is free software; you can redistribute it and/or     modify it under the terms of the GNU General Public License, version 2, as published by the Free Software Foundation. This program is distributed in the hope that it will be useful,     but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License     along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. The license text can also be found at https://www.gnu.org/     licenses/gpl-2.0.html (https://www.gnu.org/licenses/gpl-2.0.html) and /usr/share/common-licenses/GPL-2 on Debian systems. --------------------------------------------------------------------- Table of Contents 1. Introduction 1.1. Reporting bugs on this document 1.2. Contributing upgrade reports 1.3. Sources for this document 2. What's new in Debian 10 2.1. Supported architectures 2.2. What's new in the distribution? 2.2.1. UEFI Secure Boot 2.2.2. AppArmor enabled per default 2.2.3. Optional hardening of APT 2.2.4. Unattended-upgrades for stable point releases 2.2.5. Substantially improved man pages for German speaking users 2.2.6. Network filtering based on nftables framework by default 2.2.7. Cryptsetup defaults to on-disk LUKS2 format 2.2.8. Driverless printing with CUPS 2.2.10 2.2.9. Basic support for Allwinner A64 based devices 2.2.10. News from Debian Med Blend 2.2.11. GNOME defaults to Wayland 2.2.12. Merged /usr on fresh installs 2.2.13. News from Debian Live team 3. Installation System 3.1. What's new in the installation system? 3.1.1. Automated installation 4. Upgrades from Debian 9 (stretch) 4.1. Preparing for the upgrade 4.1.1. Back up any data or configuration information 4.1.2. Inform users in advance 4.1.3. Prepare for downtime on services 4.1.4. Prepare for recovery 4.1.5. Prepare a safe environment for the upgrade 4.1.6. Verify network interface name support 4.2. Checking APT configuration status 4.2.1. The proposed-updates section 4.2.2. Unofficial sources 4.2.3. Disabling APT pinning 4.2.4. Checking packages status 4.3. Preparing APT source-list files 4.3.1. Adding APT Internet sources 4.3.2. Adding APT sources for a local mirror 4.3.3. Adding APT sources from optical media 4.4. Upgrading packages 4.4.1. Recording the session 4.4.2. Updating the package list 4.4.3. Make sure you have sufficient space for the upgrade 4.4.4. Minimal system upgrade 4.4.5. Upgrading the system 4.5. Possible issues during upgrade 4.5.1. Dist-upgrade fails with “Could not perform immediate configuration” 4.5.2. Expected removals 4.5.3. Conflicts or Pre-Depends loops 4.5.4. File conflicts 4.5.5. Configuration changes 4.5.6. Change of session to console 4.6. Upgrading your kernel and related packages 4.6.1. Installing a kernel metapackage 4.7. Preparing for the next release 4.7.1. Purging removed packages 4.8. Obsolete packages 4.8.1. Transitional dummy packages 5. Issues to be aware of for buster 5.1. Upgrade specific items for buster 5.1.1. Hidepid mount option for procfs unsupported 5.1.2. ypbind fails to start with -no-dbus 5.1.3. NIS server does not answer NIS client requests by default 5.1.4. sshd fails to authenticate 5.1.5. Daemons fail to start or system appears to hang during boot 5.1.6. Migrating from legacy network interface names 5.1.7. Module configuration for bonding and dummy interfaces 5.1.8. OpenSSL default version and security level raised 5.1.9. Some applications don't work in GNOME on Wayland 5.1.10. Noteworthy obsolete packages 5.1.11. Deprecated components for buster 5.1.12. Things to do post upgrade before rebooting 5.1.13. SysV init related packages no longer required 5.2. Limitations in security support 5.2.1. Security status of web browsers and their rendering engines 5.2.2. Go based packages 5.3. Package specific issues 5.3.1. Semantics for using environment variables for su changed 5.3.2. Existing PostgreSQL databases need to be reindexed 5.3.3. mutt and neomutt 5.3.4. Accessing GNOME Settings app without mouse 5.3.5. gnome-disk-utility fails to change LUKS password causing permanent data loss (buster 10.0 only) 5.3.6. evolution-ews has been dropped, and email inboxes using Exchange, Office365 or Outlook server will be removed 5.3.7. Calamares installer leaves disk encryption keys readable 5.3.8. S3QL URL changes for Amazon S3 buckets 5.3.9. Split in configuration for logrotate 5.3.10. The rescue boot option is unusable without a root password 6. More information on Debian 6.1. Further reading 6.2. Getting help 6.2.1. Mailing lists 6.2.2. Internet Relay Chat 6.3. Reporting bugs 6.4. Contributing to Debian A. Managing your stretch system before the upgrade A.1. Upgrading your stretch system A.2. Checking your APT source-list files A.3. Removing obsolete configuration files A.4. Upgrade legacy locales to UTF-8 B. Contributors to the Release Notes Index Glossary Chapter 1. Introduction     This document informs users of the Debian distribution about major changes in version 10 (codenamed buster). The release notes provide information on how to upgrade safely     from release 9 (codenamed stretch) to the current release and inform users of known potential issues they could encounter in that process. You can get the most recent version of this document from https:/ /www.debian.org/releases/buster/releasenotes (https://     www.debian.org/releases/buster/releasenotes) . If in doubt, check the date on the first page to make sure you are reading a current version. Caution     Note that it is impossible to list every known issue and that therefore a selection has been made based on a combination of the expected prevalence and impact of issues. Please note that we only support and document upgrading from the previous release of Debian (in this case, the upgrade from     stretch). If you need to upgrade from older releases, we suggest you read previous editions of the release notes and upgrade to stretch first. 1.1. Reporting bugs on this document We have attempted to test all the different upgrade steps     described in this document and to anticipate all the possible issues our users might encounter. Nevertheless, if you think you have found a bug (incorrect information or information that is missing) in this documentation, please file a bug in the bug tracking system (https://bugs.debian.org/) against the release-notes package. You     might first want to review the existing bug reports (https:// bugs.debian.org/release-notes) in case the issue you've found has already been reported. Feel free to add additional information to existing bug reports if you can contribute content for this document. We appreciate, and encourage, reports providing patches to the     document's sources. You will find more information describing how to obtain the sources of this document in Section 1.3, “Sources for this document”. 1.2. Contributing upgrade reports We welcome any information from users related to upgrades from stretch to buster. If you are willing to share information please     file a bug in the bug tracking system (https://bugs.debian.org/) against the upgrade-reports package with your results. We request that you compress any attachments that are included (using gzip).     Please include the following information when submitting your upgrade report: * The status of your package database before and after the upgrade: dpkg's status database available at /var/lib/dpkg/ status and apt's package state information, available at /var /lib/apt/extended_states. You should have made a backup before the upgrade as described at Section 4.1.1, “Back up any data or configuration information”, but you can also find     backups of /var/lib/dpkg/status in /var/backups. * Session logs created using script, as described in Section 4.4.1, “Recording the session”. * Your apt logs, available at /var/log/apt/term.log, or your aptitude logs, available at /var/log/aptitude. Note     You should take some time to review and remove any sensitive and/ or confidential information from the logs before including them in a bug report as the information will be published in a public database. 1.3. Sources for this document The source of this document is in DocBook XML format. The HTML version is generated using docbook-xsl and xsltproc. The PDF version is generated using dblatex or xmlroff. Sources for the Release Notes are available in the Git repository of the Debian     Documentation Project. You can use the web interface (https:// salsa.debian.org/ddp-team/release-notes/) to access its files individually through the web and see their changes. For more information on how to access Git please consult the Debian Documentation Project VCS information pages (https:// www.debian.org/doc/vcs) . Chapter 2. What's new in Debian 10     The Wiki (https://wiki.debian.org/NewInBuster) has more information about this topic. 2.1. Supported architectures     The following are the officially supported architectures for Debian 10: * 32-bit PC (i386) and 64-bit PC (amd64) * 64-bit ARM (arm64) * ARM EABI (armel) * ARMv7 (EABI hard-float ABI, armhf)     * MIPS (mips (big-endian) and mipsel (little-endian)) * 64-bit little-endian MIPS (mips64el) * 64-bit little-endian PowerPC (ppc64el) * IBM System z (s390x) You can read more about port status, and port-specific     information for your architecture at the Debian port web pages (https://www.debian.org/ports/) . 2.2. What's new in the distribution? This new release of Debian again comes with a lot more software than its predecessor stretch; the distribution includes over 13370 new packages, for a total of over 57703 packages. Most of the software in the distribution has been updated: over 35532     software packages (this is 62% of all packages in stretch). Also, a significant number of packages (over 7278, 13% of the packages in stretch) have for various reasons been removed from the distribution. You will not see any updates for these packages and they will be marked as "obsolete" in package management front-ends; see Section 4.8, “Obsolete packages”. Debian again ships with several desktop applications and     environments. Among others it now includes the desktop environments GNOME 3.30, KDE Plasma 5.14, LXDE 10, LXQt 0.14, MATE 1.20, and Xfce 4.12.     Productivity applications have also been upgraded, including the office suites: * LibreOffice is upgraded to version 6.1;     * Calligra is upgraded to 3.1. * GNUcash is upgraded to 3.4; With buster, Debian for the first time brings a mandatory access     control framework enabled per default. New installations of Debian buster will have AppArmor installed and enabled per default. See below for more information. Besides, buster is the first Debian release to ship with Rust     based programs such as Firefox, ripgrep, fd, exa, etc. and a significant number of Rust based libraries (more than 450). Buster ships with Rustc 1.34.     Updates of other desktop applications include the upgrade to Evolution 3.30.     Among many others, this release also includes the following software updates: +---------------------------------------------------------------+ | Package | Version in 9 | Version in 10 | | | (stretch) | (buster) | |-----------------------------+---------------+-----------------| |Apache |2.4.25 |2.4.38 | |-----------------------------+---------------+-----------------| |BIND DNS Server |9.10 |9.11 | |-----------------------------+---------------+-----------------| |Cryptsetup |1.7 |2.1 | |-----------------------------+---------------+-----------------| |Dovecot MTA |2.2.27 |2.3.4 | |-----------------------------+---------------+-----------------| |Emacs |24.5 and 25.1 |26.1 | |-----------------------------+---------------+-----------------| |Exim default e-mail server |4.89 |4.92 | |-----------------------------+---------------+-----------------| |GNU Compiler Collection as |6.3 |7.4 and 8.3 | |default compiler | | | |-----------------------------+---------------+-----------------| |GIMP |2.8.18 |2.10.8 | |-----------------------------+---------------+-----------------| |GnuPG |2.1 |2.2 | |-----------------------------+---------------+-----------------| |Inkscape |0.92.1 |0.92.4 | |-----------------------------+---------------+-----------------| |the GNU C library |2.24 |2.28 | |-----------------------------+---------------+-----------------| |lighttpd |1.4.45 |1.4.53 |     |-----------------------------+---------------+-----------------| |Linux kernel image |4.9 series |4.19 series | |-----------------------------+---------------+-----------------| |LLVM/Clang toolchain |3.7 |6.0.1 and 7.0.1 | | | |(default) | |-----------------------------+---------------+-----------------| |MariaDB |10.1 |10.3 | |-----------------------------+---------------+-----------------| |Nginx |1.10 |1.14 | |-----------------------------+---------------+-----------------| |OpenJDK |8 |11 | |-----------------------------+---------------+-----------------| |OpenSSH |7.4p1 |7.9p1 | |-----------------------------+---------------+-----------------| |Perl |5.24 |5.28 | |-----------------------------+---------------+-----------------| |PHP |7.0 |7.3 | |-----------------------------+---------------+-----------------| |Postfix MTA |3.1.8 |3.3.2 | |-----------------------------+---------------+-----------------| |PostgreSQL |9.6 |11 | |-----------------------------+---------------+-----------------| |Python 3 |3.5.3 |3.7.3 | |-----------------------------+---------------+-----------------| |Rustc |  |1.34 | |-----------------------------+---------------+-----------------| |Samba |4.5 |4.9 | |-----------------------------+---------------+-----------------| |Vim |8.0 |8.1 | +---------------------------------------------------------------+ 2.2.1. UEFI Secure Boot Secure Boot is a feature enabled on most PCs that prevents     loading unsigned code, protecting against some kinds of bootkit and rootkit.     Debian can now be installed and run on most PCs with Secure Boot enabled. It is possible to enable Secure Boot on a system that has an existing Debian installation, if it already boots using UEFI.     Before doing this, it's necessary to install shim-signed, grub-efi-amd64-signed or grub-efi-ia32-signed, and a Linux kernel package from buster.     Some features of GRUB and Linux are restricted in Secure Boot mode, to prevent modifications to their code.     More information can be found on the Debian wiki at SecureBoot (https://wiki.debian.org/SecureBoot) . 2.2.2. AppArmor enabled per default Debian buster has AppArmor enabled per default. AppArmor is a mandatory access control framework for restricting programs'     capabilities (such as mount, ptrace, and signal permissions, or file read, write, and execute access) by defining per-program profiles. The apparmor package ships with AppArmor profiles for several     programs. Some other packages, such as evince, include profiles for the programs they ship. More profiles can be found in the apparmor-profiles-extra package. AppArmor is pulled in due to a Recommends by the buster Linux     kernel package. On systems that are configured to not install recommended packages by default, the apparmor package can be installed manually in order to enable AppArmor. 2.2.3. Optional hardening of APT All methods provided by APT (e.g. http, and https) except for cdrom, gpgv, and rsh can make use of seccomp-BPF sandboxing as supplied by the Linux kernel to restrict the list of allowed system calls, and trap all others with a SIGSYS signal. This sandboxing is currently opt-in and needs to be enabled with:     APT::Sandbox::Seccomp is a boolean to turn it on/off Two options can be used to configure this further: APT::Sandbox::Seccomp::Trap is a list of names of more syscalls to trap APT::Sandbox::Seccomp::Allow is a list of names of more syscalls to allow 2.2.4. Unattended-upgrades for stable point releases Previous versions of unattended-upgrades defaulted to installing     only upgrades that came from the security suite. In buster it now also automates upgrading to the latest stable point release. For details, see the package's NEWS.Debian file. 2.2.5. Substantially improved man pages for German speaking users The documentation (man-pages) for several projects like systemd, util-linux and mutt has been substantially extended. Please     install manpages-de to benefit from the improvements. During the lifetime of buster further new/improved translations will be provided within the backports archive. 2.2.6. Network filtering based on nftables framework by default Starting with iptables v1.8.2 the binary package includes iptables-nft and iptables-legacy, two variants of the iptables command line interface. The nftables-based variant, using the     nf_tables Linux kernel subsystem, is the default in buster. The legacy variant uses the x_tables Linux kernel subsystem. The update-alternatives system can be used to select one variant or the other. This applies to all related tools and utilities: * iptables * iptables-save * iptables-restore * ip6tables * ip6tables-save     * ip6tables-restore * arptables * arptables-save * arptables-restore * ebtables * ebtables-save * ebtables-restore All these have also gained -nft and -legacy variants. The -nft option is for users who can't or don't want to migrate to the     native nftables command line interface. However, users are strongly enouraged to switch to the nftables interface rather than using iptables. nftables provides a full replacement for iptables, with much better performance, a refreshed syntax, better support for IPv4/ IPv6 dual-stack firewalls, full atomic operations for dynamic     ruleset updates, a Netlink API for third party applications, faster packet classification through enhanced generic set and map infrastructures, and many other improvements (https:// wiki.nftables.org) . This change is in line with what other major Linux distributions are doing, such as RedHat, which now uses nftables as its default     firewalling tool (https://access.redhat.com/documentation/en-us/ red_hat_enterprise_linux/8-beta/html-single/ 8.0_beta_release_notes/index#networking_2) . Also, please note that all iptables binaries are now installed in /usr/sbin instead of /sbin. A compatibility symlink is in place,     but will be dropped after the buster release cycle. Hardcoded paths to the binaries in scripts will need to be corrected and are worth avoiding. Extensive documentation is available in the package's README and     NEWS files and on the Debian Wiki (https://wiki.debian.org/ nftables) . 2.2.7. Cryptsetup defaults to on-disk LUKS2 format The cryptsetup version shipped with Debian buster uses the new     on-disk LUKS2 format. New LUKS volumes will use this format by default. Unlike the previous LUKS1 format, LUKS2 provides redundancy of     metadata, detection of metadata corruption, and configurable PBKDF algorithms. Authenticated encryption is supported as well, but still marked as experimental. Existing LUKS1 volumes will not be updated automatically. They can be converted, but not all LUKS2 features will be available     due to header size incompatibilities. See the cryptsetup (https:/ /manpages.debian.org/buster/cryptsetup) manpage for more information. Please note that the GNU GRUB bootloader doesn't support the LUKS2 format yet. See the corresponding documentation (https://     cryptsetup-team.pages.debian.net/cryptsetup/encrypted-boot.html) for further information on how to install Debian 10 with encrypted boot. 2.2.8. Driverless printing with CUPS 2.2.10 Debian 10 provides CUPS 2.2.10 and cups-filters 1.21.6. Together these give a user everything that is needed to take advantage of driverless printing (https://wiki.debian.org/DriverlessPrinting)     . The principal requirement is that a network print queue or printer offers an AirPrint service. A modern IPP printer is highly likely to be AirPrint-capable; a Debian CUPS print queue is always AirPrint-enabled. In essence, the DNS-SD (Bonjour) broadcasts from a CUPS server advertising a queue, or those from IPP printers, are capable of     being displayed in the print dialogs of applications without any action being required on the part of a user. An additional benefit is that the use of non-free vendor printing drivers and plugins can be dispensed with. A default installation of the cups package also installs the package cups-browsed; print queues and IPP printers will now be     automatically set up and managed by this utility. This is the recommended way (https://wiki.debian.org/QuickPrintQueuesCUPS) for a user to experience seamless and trouble-free driverless printing. 2.2.9. Basic support for Allwinner A64 based devices Thanks to the efforts of the linux-sunxi community (https:// linux-sunxi.org) Debian buster will have basic suport for many     devices based on the Allwinner A64 SoC. This includes FriendlyARM NanoPi A64; Olimex A64-OLinuXino and TERES-A64; PINE64 PINE A64/ A64+/A64-LTS, SOPINE, and Pinebook; SINOVOIP Banana Pi BPI-M64; and Xunlong Orange Pi Win(Plus). The essential features of these devices (e.g. serial console, ethernet, USB ports and basic video output) should work with the kernel from buster. More advanced features (e.g. audio or     accelerated video) are included or scheduled to be included in later kernels, which will be made available as usual through the backports archive (https://backports.debian.org) . See also the status page (https://linux-sunxi.org/Linux_mainlining_effort) for the Linux mainlining effort. 2.2.10. News from Debian Med Blend The Debian Med team has added several new packages and updates     for software targeting life sciences and medicine. The effort to add Continuous Integration support for the packages in this field was (and will be) continued. To install packages maintained by the Debian Med team, install the metapackages named med-*, which are at version 3.3 for Debian     buster. Feel free to visit the Debian Med tasks pages (http:// blends.debian.org/med/tasks) to see the full range of biological and medical software available in Debian. 2.2.11. GNOME defaults to Wayland Following upstream, GNOME in buster defaults to using the Wayland     display server instead of Xorg. Wayland has a simpler and more modern design, which has advantages for security. The Xorg display server is still installed by default and the default display manager still allows you to choose it as the     display server for the next session, which may be needed if you want to use some applications (see Section 5.1.9, “Some applications don't work in GNOME on Wayland”). People requiring accessibility features of the display server,     e.g. global keyboard shortcuts, are recommended to use Xorg instead of Wayland. 2.2.12. Merged /usr on fresh installs On fresh installs, the content of /bin, /sbin and /lib will be installed into their /usr counterpart by default. /bin, /sbin and /lib will be soft-links pointing at their directory counterpart under /usr/. In graphical form: /bin → /usr/bin /sbin → /usr/sbin     /lib → /usr/lib When upgrading to buster, systems are left as they are, although the usrmerge package exists to do the conversion if desired. The freedesktop.org (https://www.freedesktop.org) project hosts a Wiki (https://www.freedesktop.org/wiki/Software/systemd/ TheCaseForTheUsrMerge/) with most of the rationale. This change shouldn't impact normal users that only run packages     provided by Debian, but it may be something that people that use or build third party software want to be aware of. 2.2.13. News from Debian Live team The Debian Live team is proud to introduce LXQt live ISOs as a new flavor. LXQt is a lightweight Qt desktop environment. It will     not get in your way. It will not hang or slow down your system. It is focused on being a classic desktop with a modern look and feel. The LXQt desktop environment offered in the Debian Live LXQt project is pure, unmodified, so you will get the standard desktop experience that the LXQt developers created for their popular     operating system. Users are presented with the standard LXQt layout comprised of a single panel (taskbar) located on the bottom edge of the screen, which includes various useful applets, such as the Main Menu, task manager, app launcher, system tray area, and integrated calendar. The buster live images come with something new that a bunch of other distributions have also adopted, which is the Calamares installer. Calamares is an independent installer project (they     call it “The universal installer framework”) which offers a Qt based interface for installing a system. It doesn't replace debian-installer on the live images; rather, it serves a different audience. Calamares is really easy to use, with friendly guided partitioning and really simple full-disk encryption setup. It doesn't cover all the advanced features of debian-installer (although it very recently got RAID support) and it doesn't have     an unattended install mode either. However, for 95%+ of desktop and laptop users, Calamares is a much easier way to get a system installed, which makes it very appropriate for live systems. For anyone who needs anything more complicated, or who's doing a mass-install, debian-installer is still available in both text and GUI forms. Debian Live Buster re-introduces the standard live image. This is a basic Debian image that contains a base Debian system without     any graphical user interface. Because it installs from a squashfs image rather than installing the system files using dpkg, installation times are a lot faster than installing from a minimal Debian installation image. Chapter 3. Installation System The Debian Installer is the official installation system for     Debian. It offers a variety of installation methods. Which methods are available to install your system depends on your architecture. Images of the installer for buster can be found together with the     Installation Guide on the Debian website (https://www.debian.org/ releases/buster/debian-installer/) .     The Installation Guide is also included on the first media of the official Debian DVD (CD/blu-ray) sets, at:     /doc/install/manual/language/index.html You may also want to check the errata (https://www.debian.org/     releases/buster/debian-installer/index#errata) for debian-installer for a list of known issues. 3.1. What's new in the installation system? There has been a lot of development on the Debian Installer since     its previous official release with Debian 9, resulting in improved hardware support and some exciting new features or improvements. Most notably there is the initial support for UEFI Secure Boot     (see Section 2.2.1, “UEFI Secure Boot”), which has been added to the installation images. If you are interested in an overview of the detailed changes since stretch, please check the release announcements for the     buster beta and RC releases available from the Debian Installer's news history (https://www.debian.org/devel/debian-installer/News /) . 3.1.1. Automated installation Some changes mentioned in the previous section also imply changes in the support in the installer for automated installation using     preconfiguration files. This means that if you have existing preconfiguration files that worked with the stretch installer, you cannot expect these to work with the new installer without modification. The Installation Guide (https://www.debian.org/releases/buster/     installmanual) has an updated separate appendix with extensive documentation on using preconfiguration. Chapter 4. Upgrades from Debian 9 (stretch) 4.1. Preparing for the upgrade We suggest that before upgrading you also read the information in Chapter 5, Issues to be aware of for buster. That chapter covers     potential issues which are not directly related to the upgrade process but could still be important to know about before you begin. 4.1.1. Back up any data or configuration information Before upgrading your system, it is strongly recommended that you make a full backup, or at least back up any data or configuration     information you can't afford to lose. The upgrade tools and process are quite reliable, but a hardware failure in the middle of an upgrade could result in a severely damaged system. The main things you'll want to back up are the contents of /etc, /var/lib/dpkg, /var/lib/apt/extended_states and the output of     dpkg --get-selections "*" (the quotes are important). If you use aptitude to manage packages on your system, you will also want to back up /var/lib/aptitude/pkgstates. The upgrade process itself does not modify anything in the /home directory. However, some applications (e.g. parts of the Mozilla suite, and the GNOME and KDE desktop environments) are known to overwrite existing user settings with new defaults when a new     version of the application is first started by a user. As a precaution, you may want to make a backup of the hidden files and directories (“dotfiles”) in users' home directories. This backup may help to restore or recreate the old settings. You may also want to inform users about this. Any package installation operation must be run with superuser     privileges, so either log in as root or use su or sudo to gain the necessary access rights.     The upgrade has a few preconditions; you should check them before actually executing the upgrade. 4.1.2. Inform users in advance It's wise to inform all users in advance of any upgrades you're     planning, although users accessing your system via an ssh connection should notice little during the upgrade, and should be able to continue working.     If you wish to take extra precautions, back up or unmount the / home partition before upgrading. You will have to do a kernel upgrade when upgrading to buster, so     a reboot will be necessary. Typically, this will be done after the upgrade is finished. 4.1.3. Prepare for downtime on services There might be services that are offered by the system which are associated with packages that will be included in the upgrade. If     this is the case, please note that, during the upgrade, these services will be stopped while their associated packages are being replaced and configured. During this time, these services will not be available. The precise downtime for these services will vary depending on the number of packages being upgraded in the system, and it also includes the time the system administrator spends answering any     configuration questions from package upgrades. Notice that if the upgrade process is left unattended and the system requests input during the upgrade there is a high possibility of services being unavailable^[1] for a significant period of time. If the system being upgraded provides critical services for your users or the network^[2], you can reduce the downtime if you do a minimal system upgrade, as described in Section 4.4.4, “Minimal system upgrade”, followed by a kernel upgrade and reboot, and     then upgrade the packages associated with your critical services. Upgrade these packages prior to doing the full upgrade described in Section 4.4.5, “Upgrading the system”. This way you can ensure that these critical services are running and available through the full upgrade process, and their downtime is reduced. 4.1.4. Prepare for recovery Although Debian tries to ensure that your system stays bootable at all times, there is always a chance that you may experience     problems rebooting your system after the upgrade. Known potential issues are documented in this and the next chapters of these Release Notes. For this reason it makes sense to ensure that you will be able to     recover if your system should fail to reboot or, for remotely managed systems, fail to bring up networking. If you are upgrading remotely via an ssh link it is recommended that you take the necessary precautions to be able to access the server through a remote serial terminal. There is a chance that,     after upgrading the kernel and rebooting, you will have to fix the system configuration through a local console. Also, if the system is rebooted accidentally in the middle of an upgrade there is a chance you will need to recover using a local console. For emergency recovery we generally recommend using the rescue mode of the buster Debian Installer. The advantage of using the installer is that you can choose between its many methods to find     one that best suits your situation. For more information, please consult the section “Recovering a Broken System” in chapter 8 of the Installation Guide (https://www.debian.org/releases/buster/ installmanual) and the Debian Installer FAQ (https:// wiki.debian.org/DebianInstaller/FAQ) . If that fails, you will need an alternative way to boot your system so you can access and repair it. One option is to use a     special rescue image or a Linux live CD. After booting from that, you should be able to mount your root file system and chroot into it to investigate and fix the problem. 4.1.4.1. Debug shell during boot using initrd The initramfs-tools package includes a debug shell^[3] in the initrds it generates. If for example the initrd is unable to     mount your root file system, you will be dropped into this debug shell which has basic commands available to help trace the problem and possibly fix it. Basic things to check are: presence of correct device files in / dev; what modules are loaded (cat /proc/modules); output of dmesg     for errors loading drivers. The output of dmesg will also show what device files have been assigned to which disks; you should check that against the output of echo $ROOT to make sure that the root file system is on the expected device. If you do manage to fix the problem, typing exit will quit the     debug shell and continue the boot process at the point it failed. Of course you will also need to fix the underlying problem and regenerate the initrd so the next boot won't fail again. 4.1.4.2. Debug shell during boot using systemd If the boot fails under systemd, it is possible to obtain a debug     root shell by changing the kernel command line. If the basic boot succeeds, but some services fail to start, it may be useful to add systemd.unit=rescue.target to the kernel parameters. Otherwise, the kernel parameter systemd.unit=emergency.target will provide you with a root shell at the earliest possible     point. However, this is done before mounting the root file system with read-write permissions. You will have to do that manually with:     # mount -o remount,rw / More information on debugging a broken boot under systemd can be     found in the Diagnosing Boot Problems (https://freedesktop.org/ wiki/Software/systemd/Debugging/) article. 4.1.5. Prepare a safe environment for the upgrade Important     If you are using some VPN services (such as tinc) consider that they might not be available throughout the upgrade process. Please see Section 4.1.3, “Prepare for downtime on services”. In order to gain extra safety margin when upgrading remotely, we suggest that you run upgrade processes in the virtual console     provided by the screen program, which enables safe reconnection and ensures the upgrade process is not interrupted even if the remote connection process temporarily fails. 4.1.6. Verify network interface name support Systems upgraded from older releases that still use network interfaces with names like eth0 or wlan0 are at risk of losing     networking once they switch to buster; see Section 5.1.6, “Migrating from legacy network interface names” for migration instructions. 4.2. Checking APT configuration status The upgrade process described in this chapter has been designed for “pure” Debian stable systems. If your APT configuration     mentions additional sources besides stretch, or if you have installed packages from other releases or from third parties, then to ensure a reliable upgrade process you may wish to begin by removing these complicating factors. The main configuration file that APT uses to decide what sources it should download packages from is /etc/apt/sources.list, but it can also use files in the /etc/apt/sources.list.d/ directory -     for details see sources.list(5) (https://manpages.debian.org/ buster//buster/apt/sources.list.5.html) . If your system is using multiple source-list files then you will need to ensure they stay consistent. Below there are two methods for finding installed packages that did not come from Debian, using either aptitude or apt-forktracer . Please note that neither of them are 100% accurate (e.g. the aptitude example will list packages that were once provided by     Debian but no longer are, such as old kernel packages). $ aptitude search '~i(!~ODebian)' $ apt-forktracer | sort Direct upgrades from Debian releases older than 9 (stretch) are     not supported. Please follow the instructions in the Release Notes for Debian 9 (https://www.debian.org/releases/stretch/ releasenotes) to upgrade to Debian 9 first. This procedure also assumes your system has been updated to the     latest point release of stretch. If you have not done this or are unsure, follow the instructions in Section A.1, “Upgrading your stretch system”. You should also make sure the package database is ready before proceeding with the upgrade. If you are a user of another package manager like aptitude or synaptic, review any pending actions. A     package scheduled for installation or removal might interfere with the upgrade procedure. Note that correcting this is only possible if your APT source-list files still point to stretch and not to stable or buster; see Section A.2, “Checking your APT source-list files”.     It is a good idea to remove obsolete packages from your system before upgrading. 4.2.1. The proposed-updates section If you have listed the proposed-updates section in your APT     source-list files, you should remove it before attempting to upgrade your system. This is a precaution to reduce the likelihood of conflicts. 4.2.2. Unofficial sources If you have any non-Debian packages on your system, you should be aware that these may be removed during the upgrade because of conflicting dependencies. If these packages were installed by     adding an extra package archive in your APT source-list files, you should check if that archive also offers packages compiled for buster and change the source item accordingly at the same time as your source items for Debian packages. Some users may have unofficial backported “newer” versions of packages that are in Debian installed on their stretch system.     Such packages are most likely to cause problems during an upgrade as they may result in file conflicts^[4]. Section 4.5, “Possible issues during upgrade” has some information on how to deal with file conflicts if they should occur. 4.2.3. Disabling APT pinning If you have configured APT to install certain packages from a distribution other than stable (e.g. from testing), you may have     to change your APT pinning configuration (stored in /etc/apt/ preferences and /etc/apt/preferences.d/) to allow the upgrade of packages to the versions in the new stable release. Further information on APT pinning can be found in apt_preferences(5). 4.2.4. Checking packages status Regardless of the method used for upgrading, it is recommended that you check the status of all packages first, and verify that     all packages are in an upgradable state. The following command will show any packages which have a status of Half-Installed or Failed-Config, and those with any error status.     # dpkg --audit     You could also inspect the state of all packages on your system using aptitude or with commands such as     # dpkg -l | pager     or     # dpkg --get-selections "*" > ~/curr-pkgs.txt It is desirable to remove any holds before upgrading. If any     package that is essential for the upgrade is on hold, the upgrade will fail. Note that aptitude uses a different method for registering     packages that are on hold than apt and dselect. You can identify packages on hold for aptitude with     # aptitude search "~ahold"     If you want to check which packages you had on hold for apt, you should use     # dpkg --get-selections | grep 'hold$' If you changed and recompiled a package locally, and didn't     rename it or put an epoch in the version, you must put it on hold to prevent it from being upgraded.     The “hold” package state for apt can be changed using:     # echo package_name hold | dpkg --set-selections     Replace hold with install to unset the “hold” state. If there is anything you need to fix, it is best to make sure     your APT source-list files still refer to stretch as explained in Section A.2, “Checking your APT source-list files”. 4.3. Preparing APT source-list files Before starting the upgrade you must reconfigure APT's     source-list files (/etc/apt/sources.list and files under /etc/apt /sources.list.d/). APT will consider all packages that can be found via any configured archive, and install the package with the highest     version number, giving priority to the first entry in the files. Thus, if you have multiple mirror locations, list first the ones on local hard disks, then CD-ROMs, and then remote mirrors. A release can often be referred to both by its codename (e.g. stretch, buster) and by its status name (i.e. oldstable, stable, testing, unstable). Referring to a release by its codename has the advantage that you will never be surprised by a new release     and for this reason is the approach taken here. It does of course mean that you will have to watch out for release announcements yourself. If you use the status name instead, you will just see loads of updates for packages available as soon as a release has happened. Debian provides two announcement mailing lists to help you stay up to date on relevant information related to Debian releases: * By subscribing to the Debian announcement mailing list (https://lists.debian.org/debian-announce/) , you will     receive a notification every time Debian makes a new release. Such as when buster changes from e.g. stable to oldstable. * By subscribing to the Debian security announcement mailing list (https://lists.debian.org/debian-security-announce/) , you will receive a notification every time Debian publishes a security announcement. 4.3.1. Adding APT Internet sources On new installations the default is for APT to be set up to use the Debian APT CDN service, which should ensure that packages are automatically downloaded from a server near you in network terms.     As this is a relatively new service, older installations may have configuration that still points to one of the main Debian Internet servers or one of the mirrors. If you haven't done so yet, it is recommended to switch over to the use of the CDN service in your APT configuration.     To make use of the CDN service, add a line like this to your APT source configuration (assuming you are using main and contrib):     deb http://deb.debian.org/debian buster main contrib     After adding your new sources, disable the previously existing “ deb” lines by placing a hash sign (#) in front of them.     However, if you get better results using a specific mirror that is close to you in network terms, this option is still available. Debian mirror addresses can be found at https://www.debian.org/     distrib/ftplist (https://www.debian.org/distrib/ftplist) (look at the “list of Debian mirrors” section). For example, suppose your closest Debian mirror is http://     mirrors.kernel.org. If you inspect that mirror with a web browser, you will notice that the main directories are organized like this: http://mirrors.kernel.org/debian/dists/buster/main/binary-arm64/...     http://mirrors.kernel.org/debian/dists/buster/contrib/binary-arm64/...     To configure APT to use a given mirror, add a line like this (again, assuming you are using main and contrib):     deb http://mirrors.kernel.org/debian buster main contrib Note that the “dists” is added implicitly, and the arguments     after the release name are used to expand the path into multiple directories.     Again, after adding your new sources, disable the previously existing archive entries. 4.3.2. Adding APT sources for a local mirror Instead of using remote package mirrors, you may wish to modify     the APT source-list files to use a mirror on a local disk (possibly mounted over NFS).     For example, your package mirror may be under /var/local/debian/, and have main directories like this: /var/local/debian/dists/buster/main/binary-arm64/...     /var/local/debian/dists/buster/contrib/binary-arm64/...     To use this with apt, add this line to your sources.list file:     deb file:/var/local/debian buster main contrib Note that the “dists” is added implicitly, and the arguments     after the release name are used to expand the path into multiple directories. After adding your new sources, disable the previously existing     archive entries in the APT source-list files by placing a hash sign (#) in front of them. 4.3.3. Adding APT sources from optical media If you want to use only DVDs (or CDs or Blu-ray Discs), comment     out the existing entries in all the APT source-list files by placing a hash sign (#) in front of them. Make sure there is a line in /etc/fstab that enables mounting     your CD-ROM drive at the /media/cdrom mount point. For example, if /dev/sr0 is your CD-ROM drive, /etc/fstab should contain a line like:     /dev/sr0 /media/cdrom auto noauto,ro 0 0     Note that there must be no spaces between the words noauto,ro in the fourth field.     To verify it works, insert a CD and try running # mount /media/cdrom # this will mount the CD to the mount point     # ls -alF /media/cdrom # this should show the CD's root directory # umount /media/cdrom # this will unmount the CD     Next, run:     # apt-cdrom add     for each Debian Binary CD-ROM you have, to add the data about each CD to APT's database. 4.4. Upgrading packages     The recommended way to upgrade from previous Debian releases is to use the package management tool apt. Note     apt is meant for interactive use, and should not be used in scripts. In scripts one should use apt-get, which has a stable output better suitable for parsing.     Don't forget to mount all needed partitions (notably the root and /usr partitions) read-write, with a command like:     # mount -o remount,rw /mountpoint Next you should double-check that the APT source entries (in /etc /apt/sources.list and files under /etc/apt/sources.list.d/) refer either to “buster” or to “stable”. There should not be any sources entries pointing to stretch.     +--------------------------------------------------+ |Note | | | |Source lines for a CD-ROM might sometimes refer to| |“unstable”; although this may be confusing, you | |should not change it. | +--------------------------------------------------+ 4.4.1. Recording the session It is strongly recommended that you use the /usr/bin/script program to record a transcript of the upgrade session. Then if a     problem occurs, you will have a log of what happened, and if needed, can provide exact information in a bug report. To start the recording, type:     # script -t 2>~/upgrade-busterstep.time -a ~/upgrade-busterstep.script or similar. If you have to rerun the typescript (e.g. if you have to reboot the system) use different step values to indicate which     step of the upgrade you are logging. Do not put the typescript file in a temporary directory such as /tmp or /var/tmp (files in those directories may be deleted during the upgrade or during any restart). The typescript will also allow you to review information that has     scrolled off-screen. If you are at the system's console, just switch to VT2 (using Alt+F2) and, after logging in, use less -R ~root/upgrade-buster.script to view the file.     After you have completed the upgrade, you can stop script by typing exit at the prompt. apt will also log the changed package states in /var/log/apt/ history.log and the terminal output in /var/log/apt/term.log.     dpkg will, in addition, log all package state changes in /var/log /dpkg.log. If you use aptitude, it will also log state changes in /var/log/aptitude.     If you have used the -t switch for script you can use the scriptreplay program to replay the whole session:     # scriptreplay ~/upgrade-busterstep.time ~/upgrade-busterstep.script 4.4.2. Updating the package list     First the list of available packages for the new release needs to be fetched. This is done by executing:     # apt update Note     Users of apt-secure may find issues when using aptitude or apt-get. For apt-get, you can use apt-get update --allow-releaseinfo-change. 4.4.3. Make sure you have sufficient space for the upgrade You have to make sure before upgrading your system that you will have sufficient hard disk space when you start the full system upgrade described in Section 4.4.5, “Upgrading the system”. First, any package needed for installation that is fetched from the network is stored in /var/cache/apt/archives (and the partial / subdirectory, during download), so you must make sure you have     enough space on the file system partition that holds /var/ to temporarily download the packages that will be installed in your system. After the download, you will probably need more space in other file system partitions in order to both install upgraded packages (which might contain bigger binaries or more data) and new packages that will be pulled in for the upgrade. If your system does not have sufficient space you might end up with an incomplete upgrade that is difficult to recover from. apt can show you detailed information about the disk space needed     for the installation. Before executing the upgrade, you can see this estimate by running: # apt -o APT::Get::Trivial-Only=true full-upgrade [ ... ]     XXX upgraded, XXX newly installed, XXX to remove and XXX not upgraded. Need to get xx.xMB of archives. After this operation, AAAMB of additional disk space will be used. Note Running this command at the beginning of the upgrade process may     give an error, for the reasons described in the next sections. In that case you will need to wait until you've done the minimal system upgrade as in Section 4.4.4, “Minimal system upgrade” before running this command to estimate the disk space.     If you do not have enough space for the upgrade, apt will warn you with a message like this:     E: You don't have enough free space in /var/cache/apt/archives/.     In this situation, make sure you free up space beforehand. You can: * Remove packages that have been previously downloaded for installation (at /var/cache/apt/archives). Cleaning up the package cache by running apt clean will remove all previously downloaded package files. * Remove forgotten packages. If you have used aptitude or apt to manually install packages in stretch it will have kept track of those packages you manually installed, and will be able to mark as redundant those packages pulled in by dependencies alone which are no longer needed due to a package being removed. They will not mark for removal packages that you manually installed. To remove automatically installed packages that are no longer used, run: # apt autoremove You can also use deborphan, debfoster, or cruft to find redundant packages. Do not blindly remove the packages these tools present, especially if you are using aggressive non-default options that are prone to false positives. It is highly recommended that you manually review the packages suggested for removal (i.e. their contents, sizes, and descriptions) before you remove them. * Remove packages that take up too much space and are not currently needed (you can always reinstall them after the upgrade). If you have popularity-contest installed, you can use popcon-largest-unused to list the packages you do not use that occupy the most space. You can find the packages that just take up the most disk space with dpigs (available in the debian-goodies package) or with wajig (running wajig size). They can also be found with aptitude. Start aptitude in full-terminal mode, select Views → New Flat Package List, press l and enter ~i, then press S and enter ~installsize. This will give you a handy list to work with. * Remove translations and localization files from the system if they are not needed. You can install the localepurge package and configure it so that only a few selected locales are kept in the system. This will reduce the disk space consumed at /usr/share/ locale. * Temporarily move to another system, or permanently remove, system logs residing under /var/log/.     * Use a temporary /var/cache/apt/archives: You can use a temporary cache directory from another filesystem (USB storage device, temporary hard disk, filesystem already in use, ...). +-----------------------------------------------------+ |Note | | | |Do not use an NFS mount as the network connection | |could be interrupted during the upgrade. | +-----------------------------------------------------+ For example, if you have a USB drive mounted on /media/usbkey: 1. remove the packages that have been previously downloaded for installation: # apt clean 2. copy the directory /var/cache/apt/archives to the USB drive: # cp -ax /var/cache/apt/archives /media/usbkey/ 3. mount the temporary cache directory on the current one: # mount --bind /media/usbkey/archives /var/cache/apt/archives 4. after the upgrade, restore the original /var/cache/apt/ archives directory: # umount /media/usbkey/archives 5. remove the remaining /media/usbkey/archives. You can create the temporary cache directory on whatever filesystem is mounted on your system. * Do a minimal upgrade of the system (see Section 4.4.4, “Minimal system upgrade”) or partial upgrades of the system followed by a full upgrade. This will make it possible to upgrade the system partially, and allow you to clean the package cache before the full upgrade. Note that in order to safely remove packages, it is advisable to     switch your APT source-list files back to stretch as described in Section A.2, “Checking your APT source-list files”. 4.4.4. Minimal system upgrade In some cases, doing the full upgrade (as described below) directly might remove large numbers of packages that you will     want to keep. We therefore recommend a two-part upgrade process: first a minimal upgrade to overcome these conflicts, then a full upgrade as described in Section 4.4.5, “Upgrading the system”.     To do this, first run:     # apt-get upgrade This has the effect of upgrading those packages which can be     upgraded without requiring any other packages to be removed or installed. The minimal system upgrade can also be useful when the system is     tight on space and a full upgrade cannot be run due to space constraints. If the apt-listchanges package is installed, it will (in its     default configuration) show important information about upgraded packages in a pager after downloading the packages. Press q after reading to exit the pager and continue the upgrade. 4.4.5. Upgrading the system     Once you have taken the previous steps, you are now ready to continue with the main part of the upgrade. Execute:     # apt full-upgrade This will perform a complete upgrade of the system, installing the newest available versions of all packages, and resolving all     possible dependency changes between packages in different releases. If necessary, it will install some new packages (usually new library versions, or renamed packages), and remove any conflicting obsoleted packages. When upgrading from a set of CDs/DVDs/BDs, you will probably be asked to insert specific discs at several points during the     upgrade. You might have to insert the same disc multiple times; this is due to inter-related packages that have been spread out over the discs. New versions of currently installed packages that cannot be upgraded without changing the install status of another package     will be left at their current version (displayed as “held back”). This can be resolved by either using aptitude to choose these packages for installation or by trying apt install package. 4.5. Possible issues during upgrade     The following sections describe known issues that might appear during an upgrade to buster. 4.5.1. Dist-upgrade fails with “Could not perform immediate configuration” In some cases the apt full-upgrade step can fail after downloading packages with:     E: Could not perform immediate configuration on 'package'. Please see man 5 apt.conf under APT::Immediate-Configure for details. If that happens, running apt full-upgrade -o     APT::Immediate-Configure=0 instead should allow the upgrade to proceed. Another possible workaround for this problem is to temporarily     add both stretch and buster sources to your APT source-list files and run apt update. 4.5.2. Expected removals The upgrade process to buster might ask for the removal of packages on the system. The precise list of packages will vary depending on the set of packages that you have installed. These     release notes give general advice on these removals, but if in doubt, it is recommended that you examine the package removals proposed by each method before proceeding. For more information about packages obsoleted in buster, see Section 4.8, “Obsolete packages”. 4.5.3. Conflicts or Pre-Depends loops Sometimes it's necessary to enable the APT::Force-LoopBreak option in APT to be able to temporarily remove an essential     package due to a Conflicts/Pre-Depends loop. apt will alert you of this and abort the upgrade. You can work around this by specifying the option -o APT::Force-LoopBreak=1 on the apt command line. It is possible that a system's dependency structure can be so     corrupt as to require manual intervention. Usually this means using apt or     # dpkg --remove package_name     to eliminate some of the offending packages, or # apt -f install     # dpkg --configure --pending     In extreme cases you might have to force re-installation with a command like     # dpkg --install /path/to/package_name.deb 4.5.4. File conflicts File conflicts should not occur if you upgrade from a “pure”     stretch system, but can occur if you have unofficial backports installed. A file conflict will result in an error like: Unpacking (from ) ... dpkg: error processing (--install): trying to overwrite `',     which is also in package dpkg-deb: subprocess paste killed by signal (Broken pipe) Errors were encountered while processing:     You can try to solve a file conflict by forcibly removing the package mentioned on the last line of the error message:     # dpkg -r --force-depends package_name     After fixing things up, you should be able to resume the upgrade by repeating the previously described apt commands. 4.5.5. Configuration changes During the upgrade, you will be asked questions regarding the configuration or re-configuration of several packages. When you are asked if any file in the /etc/init.d directory, or the /etc/     manpath.config file should be replaced by the package maintainer's version, it's usually necessary to answer “yes” to ensure system consistency. You can always revert to the old versions, since they will be saved with a .dpkg-old extension. If you're not sure what to do, write down the name of the package     or file and sort things out at a later time. You can search in the typescript file to review the information that was on the screen during the upgrade. 4.5.6. Change of session to console If you are running the upgrade using the system's local console you might find that at some points during the upgrade the console     is shifted over to a different view and you lose visibility of the upgrade process. For example, this may happen in systems with a graphical interface when the display manager is restarted. To recover the console where the upgrade was running you will have to use Ctrl+Alt+F1 (if in the graphical startup screen) or Alt+F1 (if in the local text-mode console) to switch back to the     virtual terminal 1. Replace F1 with the function key with the same number as the virtual terminal the upgrade was running in. You can also use Alt+Left Arrow or Alt+Right Arrow to switch between the different text-mode terminals. 4.6. Upgrading your kernel and related packages This section explains how to upgrade your kernel and identifies     potential issues related to this upgrade. You can either install one of the linux-image-* packages provided by Debian, or compile a customized kernel from source. Note that a lot of information in this section is based on the assumption that you will be using one of the modular Debian     kernels, together with initramfs-tools and udev. If you choose to use a custom kernel that does not require an initrd or if you use a different initrd generator, some of the information may not be relevant for you. 4.6.1. Installing a kernel metapackage When you full-upgrade from stretch to buster, it is strongly recommended that you install a linux-image-* metapackage, if you     have not done so before. These metapackages will automatically pull in a newer version of the kernel during upgrades. You can verify whether you have one installed by running:     # dpkg -l "linux-image*" | grep ^ii | grep -i meta If you do not see any output, then you will either need to     install a new linux-image package by hand or install a linux-image metapackage. To see a list of available linux-image metapackages, run:     # apt-cache search linux-image- | grep -i meta | grep -v transition If you are unsure about which package to select, run uname -r and look for a package with a similar name. For example, if you see “     4.9.0-8-amd64”, it is recommended that you install linux-image-amd64. You may also use apt to see a long description of each package in order to help choose the best one available. For example:     # apt show linux-image-amd64 You should then use apt install to install it. Once this new kernel is installed you should reboot at the next available     opportunity to get the benefits provided by the new kernel version. However, please have a look at Section 5.1.12, “Things to do post upgrade before rebooting” before performing the first reboot after the upgrade. For the more adventurous there is an easy way to compile your own custom kernel on Debian. Install the kernel sources, provided in the linux-source package. You can make use of the deb-pkg target     available in the sources' makefile for building a binary package. More information can be found in the Debian Linux Kernel Handbook (https://kernel-team.pages.debian.net/kernel-handbook/) , which can also be found as the debian-kernel-handbook package. If possible, it is to your advantage to upgrade the kernel package separately from the main full-upgrade to reduce the     chances of a temporarily non-bootable system. Note that this should only be done after the minimal upgrade process described in Section 4.4.4, “Minimal system upgrade”. 4.7. Preparing for the next release     After the upgrade there are several things you can do to prepare for the next release. * Remove newly redundant or obsolete packages as described in Section 4.4.3, “Make sure you have sufficient space for the     upgrade” and Section 4.8, “Obsolete packages”. You should review which configuration files they use and consider purging the packages to remove their configuration files. See also Section 4.7.1, “Purging removed packages”. 4.7.1. Purging removed packages It is generally advisable to purge removed packages. This is especially true if these have been removed in an earlier release     upgrade (e.g. from the upgrade to stretch) or they were provided by third-party vendors. In particular, old init.d scripts have been known to cause issues. Caution     Purging a package will generally also purge its log files, so you might want to back them up first.     The following command displays a list of all removed packages that may have configuration files left on the system (if any):     # dpkg -l | awk '/^rc/ { print $2 }' The packages can be removed by using apt purge. Assuming you want     to purge all of them in one go, you can use the following command:     # apt purge $(dpkg -l | awk '/^rc/ { print $2 }')     If you use aptitude, you can also use the following alternative to the commands above: # aptitude search '~c'     # aptitude purge '~c' 4.8. Obsolete packages Introducing lots of new packages, buster also retires and omits quite a few old packages that were in stretch. It provides no upgrade path for these obsolete packages. While nothing prevents     you from continuing to use an obsolete package where desired, the Debian project will usually discontinue security support for it a year after buster's release^[5], and will not normally provide other support in the meantime. Replacing them with available alternatives, if any, is recommended. There are many reasons why packages might have been removed from the distribution: they are no longer maintained upstream; there is no longer a Debian Developer interested in maintaining the     packages; the functionality they provide has been superseded by different software (or a new version); or they are no longer considered suitable for buster due to bugs in them. In the latter case, packages might still be present in the “unstable” distribution. Some package management front-ends provide easy ways of finding installed packages that are no longer available from any known     repository. The aptitude textual user interface lists them in the category “Obsolete and Locally Created Packages”, and they can be listed and purged from the commandline with: # aptitude search '~o'     # aptitude purge '~o' The Debian Bug Tracking System (https://bugs.debian.org/) often provides additional information on why the package was removed.     You should review both the archived bug reports for the package itself and the archived bug reports for the ftp.debian.org pseudo-package (https://bugs.debian.org/cgi-bin/pkgreport.cgi?pkg =ftp.debian.org&archive=yes) .     For a list of obsolete packages for Buster, please refer to Section 5.1.10, “Noteworthy obsolete packages”. 4.8.1. Transitional dummy packages Some packages from stretch may have been replaced in buster by transitional dummy packages, which are empty placeholders designed to simplify upgrades. If for instance an application     that was formerly a single package has been split into several, a transitional package may be provided with the same name as the old package and with appropriate dependencies to cause the new ones to be installed. After this has happened the redundant dummy package can be safely removed. The package descriptions for transitional dummy packages usually indicate their purpose. However, they are not uniform; in particular, some “dummy” packages are designed to be kept     installed, in order to pull in a full software suite, or track the current latest version of some program. You might also find deborphan with the --guess-* options (e.g. --guess-dummy) useful to detect transitional dummy packages on your system. --------------------------------------------------------------------- ^[1] If the debconf priority is set to a very high level you     might prevent configuration prompts, but services that rely on default answers that are not applicable to your system will fail to start. ^[2] For example: DNS or DHCP services, especially when there is     no redundancy or failover. In the DHCP case end-users might be disconnected from the network if the lease time is lower than the time it takes for the upgrade process to complete.     ^[3] This feature can be disabled by adding the parameter panic=0 to your boot parameters. ^[4] Debian's package management system normally does not allow a     package to remove or replace a file owned by another package unless it has been defined to replace that package. ^[5] Or for as long as there is not another release in that time     frame. Typically only two stable releases are supported at any given time. Chapter 5. Issues to be aware of for buster Sometimes, changes introduced in a new release have side-effects we cannot reasonably avoid, or they expose bugs somewhere else.     This section documents issues we are aware of. Please also read the errata, the relevant packages' documentation, bug reports, and other information mentioned in Section 6.1, “Further reading” . 5.1. Upgrade specific items for buster     This section covers items related to the upgrade from stretch to buster. 5.1.1. Hidepid mount option for procfs unsupported Using the hidepid mount option for /proc is known to cause problems with current versions of systemd, and is considered by systemd upstream to be an unsupported configuration. Users who     have modified /etc/fstab to enable this option are advised to disable it before the upgrade, to ensure login sessions work on buster. (A possible route to re-enabling it is outlined on the wiki's Hardening (https://wiki.debian.org/Hardening# Mounting_.2Fproc_with_hidepid) page.) 5.1.2. ypbind fails to start with -no-dbus The default options of ypbind have changed. However, if you have modified this file the old default will not be updated and you     must make sure that the YPBINDARGS= option in /etc/default/nis does not include -no-dbus. With -no-dbus present, ypbind will fail to start, and you may not be able to log in. For more info see bug #906436 (https://bugs.debian.org/906436) . 5.1.3. NIS server does not answer NIS client requests by default The default behavior of rpcbind has changed to no longer answer remote calls from NIS clients. On NIS servers you will need to     add the (Debian-specific) -r flag to the command line options of rpcbind, otherwise users will not be able to log into your NIS client machines. For more info see bug #935492 (https:// bugs.debian.org/935492) . 5.1.4. sshd fails to authenticate The semantics of PubkeyAcceptedKeyTypes and the similar HostbasedAcceptedKeyTypes options for sshd have changed. These now specify signature algorithms that are accepted for their respective authentication mechanism, where previously they     specified accepted key types. This distinction matters when using the RSA/SHA2 signature algorithms rsa-sha2-256, rsa-sha2-512 and their certificate counterparts. Configurations that override these options but omit these algorithm names may cause unexpected authentication failures.     No action is required for configurations that accept the default for these options. 5.1.5. Daemons fail to start or system appears to hang during boot Due to systemd needing entropy during boot and the kernel treating such calls as blocking when available entropy is low, the system may hang for minutes to hours until the randomness     subsystem is sufficiently initialized (random: crng init done). For amd64 systems supporting the RDRAND instruction this issue is avoided by the Debian kernel using this instruction by default (CONFIG_RANDOM_TRUST_CPU). Non-amd64 systems and some types of virtual machines need to provide a different source of entropy to continue fast booting.     haveged has been chosen for this within the Debian Installer project and may be a valid option if hardware entropy is not available on the system. On virtual machines consider forwarding entropy from the host to the VMs via virtio_rng. If you read this after upgrading a remote system to buster, ping     the system on the network continuously as this adds entropy to the randomness pool and the system will eventually be reachable by ssh again. See the wiki (https://wiki.debian.org/BoottimeEntropyStarvation)     and DLange's overview of the issue (https://daniel-lange.com/ archives/152-hello-buster.html) for other options. 5.1.6. Migrating from legacy network interface names If your system was upgraded from an earlier release, and still uses the old-style network interface names that were deprecated with stretch (such as eth0 or wlan0), you should be aware that the mechanism of defining their names via /etc/udev/rules.d/ 70-persistent-net.rules is officially not supported by udev in     buster (while it may still work in some cases). To avoid the danger of your machine losing networking after the upgrade to buster, it is recommended that you migrate in advance to the new naming scheme (usually meaning names like enp0s1 or wlp2s5, which incorporate PCI bus- and slot-numbers). Take care to update any interface names hard-coded in configuration for firewalls, ifupdown, and so on. The alternative is to switch to a supported mechanism for enforcing the old naming scheme, such as a systemd .link file     (see systemd.link(5) (https://manpages.debian.org/buster/ systemd.link) ). The net.ifnames=0 kernel commandline option might also work for systems with only one network interface (of a given type).     To find the new-style names that will be used, first find the current names of the relevant interfaces:     $ echo /sys/class/net/[ew]* For each of these names, check whether it is used in     configuration files, and what name udev would prefer to use for it: $ sudo rgrep -w eth0 /etc     $ udevadm test-builtin net_id /sys/class/net/eth0 2>/dev/null This should give enough information to devise a migration plan.     (If the udevadm output includes an “onboard” or “slot” name, that takes priority; MAC-based names are normally treated as a fallback, but may be needed for USB network hardware.) Once you are ready to carry out the switch, disable 70-persistent-net.rules either by renaming it or by commenting     out individual lines. On virtual machines you will need to remove the files /etc/systemd/network/99-default.link and (if using virtio network devices) /etc/systemd/network/ 50-virtio-kernel-names.link. Then rebuild the initrd:     $ sudo update-initramfs -u and reboot. Your system should now have new-style network     interface names. Adjust any remaining configuration files, and test your system. See the wiki (https://wiki.debian.org/NetworkInterfaceNames) ,     upstream documentation (https://www.freedesktop.org/software/ systemd/man/systemd.net-naming-scheme.html) , and the udev README.Debian for further information. 5.1.7. Module configuration for bonding and dummy interfaces Systems using channel bonding and/or dummy interfaces, for instance to configure a machine as a router, may encounter     problems upgrading to buster. New versions of systemd install a file /lib/modprobe.d/systemd.conf (intended to simplify configuration via systemd-networkd) which contains the lines options bonding max_bonds=0     options dummy numdummies=0 Admins who were depending on different values will need to ensure they are set in the correct way to take precedence. A file in / etc/modprobe.d will override one with the same name under /lib/     modprobe.d, but the names are processed in alphabetical order, so /lib/modprobe.d/systemd.conf follows and overrides (for instance) /etc/modprobe.d/dummy.conf. Make sure that any local configuration file has a name that sorts after “systemd.conf”, such as “/etc/modprobe.d/zz-local.conf”. 5.1.8. OpenSSL default version and security level raised     Following various security recommendations, the default minimum TLS version has been changed from TLSv1 to TLSv1.2. The default security level for TLS connections has also been increased from level 1 to level 2. This moves from the 80 bit     security level to the 112 bit security level and will require 2048 bit or larger RSA and DHE keys, 224 bit or larger ECC keys, and SHA-2. The system wide settings can be changed in /etc/ssl/openssl.cnf.     Applications might also have an application specific way to override the defaults. In the default /etc/ssl/openssl.cnf there is a MinProtocol and CipherString line. The CipherString can also set the security level. Information about the security levels can be found in the SSL_CTX_set_security_level(3ssl) (https://manpages.debian.org/     buster/SSL_CTX_set_security_level(3ssl)) manpage. The list of valid strings for the minimum protocol version can be found in SSL_CONF_cmd(3ssl) (https://manpages.debian.org/buster/ SSL_CONF_cmd(3ssl)) . Other information can be found in ciphers (1ssl) (https://manpages.debian.org/buster/ciphers(1ssl)) and config(5ssl) (https://manpages.debian.org/buster/config(5ssl)) . Changing the system wide defaults in /etc/ssl/openssl.cnf back to their previous values can be done by setting:     MinProtocol = None CipherString = DEFAULT     It's recommended that you contact the remote site if the defaults cause problems. 5.1.9. Some applications don't work in GNOME on Wayland GNOME in buster has changed its default display server from Xorg to Wayland (see Section 2.2.11, “GNOME defaults to Wayland”). Some applications, including the popular package manager synaptic     , the default Simplified Chinese input method, fcitx, and most screen recording applications, have not been updated to work properly under Wayland. In order to use these packages, one needs to log in with a GNOME on Xorg session. 5.1.10. Noteworthy obsolete packages     The following is a list of known and noteworthy obsolete packages (see Section 4.8, “Obsolete packages” for a description). The list of obsolete packages includes: * The package mcelog is no longer supported with kernel versions above 4.12. rasdaemon can be used as its replacement. * The package revelation, which is used to store passwords, is not included in buster. keepass2 can import previously exported password XML files from revelation. Please make sure you export your data from revelation before upgrading, to avoid losing access to your passwords. * The package phpmyadmin is not included in buster. * ipsec-tools and racoon have been removed from buster as their source has been lagging behind in adapting to new threats.     Users are encouraged to migrate to libreswan, which has broader protocol compatibility and is being actively maintained upstream. libreswan should be fully compatible in terms of communication protocols since it implements a superset of racoon's supported protocols. * The simple MTA ssmtp has been dropped for buster. This is due to it currently not validating TLS certs; see bug #662960 (https://bugs.debian.org/662960) . * The ecryptfs-utils package is not part of buster due to an unfixed serious bug (#765854 (https://bugs.debian.org/765854) ). At the time of writing this paragraph, there was no clear advice for users of eCryptfs, except not to upgrade. 5.1.11. Deprecated components for buster With the next release of Debian 11 (codenamed bullseye) some     features will be deprecated. Users will need to migrate to other alternatives to prevent trouble when updating to Debian 11.     This includes the following features: * Python 2 will stop being supported by its upstream on January 1, 2020 (https://www.python.org/dev/peps/pep-0373/) . Debian hopes to drop python-2.7 for Debian 11. If users have functionality that relies on python, they should prepare to migrate to python3. * Icinga 1.x is EOL upstream since 2018-12-31; while the icinga package is still present, users should use the buster lifetime to migrate to Icinga 2 (icinga2 package) and Icinga Web 2 (icingaweb2 package). The icinga2-classicui package is still present to use the Icinga 1.x CGI web interface with Icinga 2, but the support for it will be removed in Icinga 2.11. Icinga Web 2 should be used instead. * The Mailman mailing list manager suite version 3 is newly available in this release. Mailman has been split up into various components; the core is available in the package     mailman3 and the full suite can be obtained via the mailman3-full metapackage. The legacy Mailman version 2.1 remains available in this release in the package mailman, so you can migrate any existing installations at your own pace. The Mailman 2.1 package will be kept in working order for the foreseeable future, but will not see any major changes or improvements. It will be removed from the first Debian release after Mailman upstream has stopped support for this branch. Everyone is encouraged to upgrade to Mailman 3, the modern release under active development. * The packages spf-milter-python and dkim-milter-python are no longer actively developed upstream, but their more feature-rich replacements, pyspf-milter and dkimpy-milter, are available in buster. Users should migrate to the new packages before the old ones are removed in bullseye. 5.1.12. Things to do post upgrade before rebooting When apt full-upgrade has finished, the “formal” upgrade is     complete. For the upgrade to buster, there are no special actions needed before performing a reboot. 5.1.13. SysV init related packages no longer required Note     This section does not apply if you have decided to stick with sysvinit-core. After the switch to systemd as default init system in Jessie and further refinements in Stretch, various SysV related packages are     no longer required and can now be purged safely via apt purge initscripts sysv-rc insserv startpar 5.2. Limitations in security support There are some packages where Debian cannot promise to provide     minimal backports for security issues. These are covered in the following subsections. Note     The package debian-security-support helps to track the security support status of installed packages. 5.2.1. Security status of web browsers and their rendering engines Debian 10 includes several browser engines which are affected by a steady stream of security vulnerabilities. The high rate of vulnerabilities and partial lack of upstream support in the form of long term branches make it very difficult to support these browsers and engines with backported security fixes.     Additionally, library interdependencies make it extremely difficult to update to newer upstream releases. Therefore, browsers built upon e.g. the webkit and khtml engines^[6] are included in buster, but not covered by security support. These browsers should not be used against untrusted websites. The webkit2gtk source package is covered by security support. For general web browser use we recommend Firefox or Chromium.     They will be kept up-to-date by rebuilding the current ESR releases for stable. The same strategy will be applied for Thunderbird. 5.2.2. Go based packages The Debian infrastructure currently doesn't properly enable rebuilding packages that statically link parts of other packages on a large scale. Until buster that hasn't been a problem in     practice, but with the growth of the Go ecosystem it means that Go based packages won't be covered by regular security support until the infrastructure is improved to deal with them maintainably.     If updates are warranted, they can only come via regular point releases, which may be slow in arriving. 5.3. Package specific issues In most cases, packages should upgrade smoothly between stretch     and buster. There are a small number of cases where some intervention may be required, either before or during the upgrade; these are detailed below on a per-package basis. 5.3.1. Semantics for using environment variables for su changed su has changed semantics in buster and no longer preserves the user environment variables DISPLAY and XAUTHORITY. If you need to     run graphical applications with su, you will have to explicitly set them to allow access to your display. See bug #905409 (https: //bugs.debian.org/905409) for an extensive discussion. 5.3.2. Existing PostgreSQL databases need to be reindexed When upgrading from stretch to buster, the glibc locale data is upgraded. Specifically, this changes how PostgreSQL sorts data in     text indexes. To avoid corruption, such indexes need to be REINDEXed immediately after upgrading the locales or locales-all packages, before putting the database back into production. Suggested command:     sudo -u postgres reindexdb --all Alternatively, upgrade the databases to PostgreSQL 11 using     pg_upgradecluster. (This uses pg_dump by default which will rebuild all indexes. Using -m upgrade or pg_upgrade is not safe because it preserves the now-wrong index ordering.)     Refer to the PostgreSQL Wiki (https://wiki.postgresql.org/wiki/ Locale_data_changes) for more information. 5.3.3. mutt and neomutt In stretch, the package mutt had patches applied from the sources at https://neomutt.org (https://neomutt.org) . Starting from     buster, the package providing /usr/bin/mutt will instead be purely based on the original sources from http://www.mutt.org (http://www.mutt.org) , and a separate neomutt package is available providing /usr/bin/neomutt. This means that some of the features that were previously     provided by mutt are no longer available. If this breaks your configuration you can install neomutt instead. 5.3.4. Accessing GNOME Settings app without mouse Without a pointing device, there is no direct way to change settings in the GNOME Settings app provided by gnome-control-center. As a work-around, you can navigate from the     sidebar to the main content by pressing the Right Arrow twice. To get back to the sidebar, you can start a search with Ctrl+F, type something, then hit Esc to cancel the search. Now you can use the Up Arrow and Down Arrow to navigate the sidebar. It is not possible to select search results with the keyboard. 5.3.5.  gnome-disk-utility fails to change LUKS password causing permanent data loss (buster 10.0 only) Users of the initial buster release images should not change the LUKS password of encrypted disks with the GNOME graphical interface for disk management. The gnome-disk-utility package in     buster had a very nasty bug (#928893) (https://bugs.debian.org/ 928893) when used to change the LUKS password: it deleted the old password but failed to correctly set the new one, making all data on the disk inaccessible. This has been fixed in the first point release. 5.3.6.  evolution-ews has been dropped, and email inboxes using Exchange, Office365 or Outlook server will be removed Users using evolution as their email client and connecting to a server running Exchange, Office365 or Outlook using the evolution-ews plugin should not upgrade to buster without backing     up data and finding an alternative solution beforehand, as evolution-ews has been dropped due to bug #926712 (https:// bugs.debian.org/926712) and their email inboxes, calendar, contact lists and tasks will be removed and will no longer be accessible with Evolution. The evolution-ews package has been reintroduced via     buster-backports. Users upgrading from stretch to buster can enable buster-backports after the upgrade and then they will be able to reinstall evolution-ews. 5.3.7.  Calamares installer leaves disk encryption keys readable When installing Debian from live media using the Calamares installer (Section 2.2.13, “News from Debian Live team”) and     selecting the full disk encryption feature, the disk's unlock key is stored in the initramfs which is world readable. This allows users with local filesystem access to read the private key and gain access to the filesystem again in the future. This can be worked around by adding UMASK=0077 to /etc/     initramfs-tools/conf.d/initramfs-permissions and running update-initramfs -u. This will recreate the initramfs without world-readable permissions. A fix for the installer is being planned (see bug #931373 (https:     //bugs.debian.org/931373) ) and will be uploaded to debian-security. In the meantime users of full disk encryption should apply the above workaround. 5.3.8.  S3QL URL changes for Amazon S3 buckets When using s3ql with Amazon S3 buckets, the configuration needs     updating for a change in the URL. The new format is: s3://// 5.3.9.  Split in configuration for logrotate The shipped configurations for /var/log/btmp and /var/log/wtmp     have been split from the main configuration file (/etc/ logrotate.conf) into separate standalone files (/etc/logrotate.d/ btmp and /etc/logrotate.d/wtmp). If you have modified /etc/logrotate.conf in this regard, make     sure to re-adjust the two new files to your needs and drop any references to (b|w)tmp from the main file, since duplicate definitions can cause errors. 5.3.10.  The rescue boot option is unusable without a root password With the implementation of sulogin now used, booting with the rescue option always requires the root password. If one has not     been set, this makes the rescue mode effectively unusable. However it is still possible to boot using the kernel parameter init=/sbin/sulogin --force To configure systemd to do the equivalent of this whenever it boots into rescue mode (also known as single mode: see systemd(1)     (https://manpages.debian.org/buster//buster/systemd/ systemd.1.html) ), run sudo systemctl edit rescue.service and create a file saying just: [Service]     Environment=SYSTEMD_SULOGIN_FORCE=1 It might also (or instead) be useful to do this for the emergency.service unit, which is started automatically in the case of certain errors (see systemd.special(7) (https://     manpages.debian.org/buster//buster/systemd/ systemd.special.7.html) ), or if emergency is added to the kernel command line (e.g. if the system can't be recovered by using the rescue mode).     For background and a discussion on the security implications see #802211 (https://bugs.debian.org//802211) . --------------------------------------------------------------------- ^[6] These engines are shipped in a number of different source     packages and the concern applies to all packages shipping them. The concern also extends to web rendering engines not explicitly mentioned here, with the exception of webkit2gtk. Chapter 6. More information on Debian 6.1. Further reading Beyond these release notes and the installation guide, further documentation on Debian is available from the Debian Documentation Project (DDP), whose goal is to create high-quality     documentation for Debian users and developers, such as the Debian Reference, Debian New Maintainers Guide, the Debian FAQ, and many more. For full details of the existing resources see the Debian Documentation website (https://www.debian.org/doc/) and the Debian Wiki (https://wiki.debian.org/) . Documentation for individual packages is installed into /usr/     share/doc/package. This may include copyright information, Debian specific details, and any upstream documentation. 6.2. Getting help There are many sources of help, advice, and support for Debian users, though these should only be considered after researching     the issue in available documentation. This section provides a short introduction to these sources which may be helpful for new Debian users. 6.2.1. Mailing lists The mailing lists of most interest to Debian users are the debian-user list (English) and other debian-user-language lists (for other languages). For information on these lists and details     of how to subscribe see https://lists.debian.org/ (https:// lists.debian.org/) . Please check the archives for answers to your question prior to posting and also adhere to standard list etiquette. 6.2.2. Internet Relay Chat Debian has an IRC channel dedicated to support and aid for Debian     users, located on the OFTC IRC network. To access the channel, point your favorite IRC client at irc.debian.org and join # debian. Please follow the channel guidelines, respecting other users     fully. The guidelines are available at the Debian Wiki (https:// wiki.debian.org/DebianIRC) .     For more information on OFTC please visit the website (http:// www.oftc.net/) . 6.3. Reporting bugs We strive to make Debian a high-quality operating system; however that does not mean that the packages we provide are totally free of bugs. Consistent with Debian's “open development” philosophy     and as a service to our users, we provide all the information on reported bugs at our own Bug Tracking System (BTS). The BTS can be browsed at https://bugs.debian.org/ (https://bugs.debian.org/) . If you find a bug in the distribution or in packaged software that is part of it, please report it so that it can be properly     fixed for future releases. Reporting bugs requires a valid e-mail address. We ask for this so that we can trace bugs and developers can get in contact with submitters should additional information be needed. You can submit a bug report using the program reportbug or manually using e-mail. You can find out more about the Bug     Tracking System and how to use it by reading the reference documentation (available at /usr/share/doc/debian if you have doc-debian installed) or online at the Bug Tracking System (https://bugs.debian.org/) . 6.4. Contributing to Debian You do not need to be an expert to contribute to Debian. By assisting users with problems on the various user support lists (https://lists.debian.org/) you are contributing to the community. Identifying (and also solving) problems related to the development of the distribution by participating on the development lists (https://lists.debian.org/) is also extremely     helpful. To maintain Debian's high-quality distribution, submit bugs (https://bugs.debian.org/) and help developers track them down and fix them. The tool how-can-i-help helps you to find suitable reported bugs to work on. If you have a way with words then you may want to contribute more actively by helping to write documentation (https://www.debian.org/doc/vcs) or translate (https://www.debian.org/international/) existing documentation into your own language. If you can dedicate more time, you could manage a piece of the Free Software collection within Debian. Especially helpful is if people adopt or maintain items that people have requested for inclusion within Debian. The Work Needing and Prospective Packages database (https://www.debian.org/devel/wnpp/) details     this information. If you have an interest in specific groups then you may find enjoyment in contributing to some of Debian's subprojects (https://www.debian.org/devel/#projects) which include ports to particular architectures and Debian Pure Blends (https://wiki.debian.org/DebianPureBlends) for specific user groups, among many others. In any case, if you are working in the free software community in any way, as a user, programmer, writer, or translator you are     already helping the free software effort. Contributing is rewarding and fun, and as well as allowing you to meet new people it gives you that warm fuzzy feeling inside. Appendix A. Managing your stretch system before the upgrade This appendix contains information on how to make sure you can     install or upgrade stretch packages before you upgrade to buster. This should only be necessary in specific situations. A.1. Upgrading your stretch system Basically this is no different from any other upgrade of stretch you've been doing. The only difference is that you first need to     make sure your package list still contains references to stretch as explained in Section A.2, “Checking your APT source-list files”.     If you upgrade your system using a Debian mirror, it will automatically be upgraded to the latest stretch point release. A.2. Checking your APT source-list files If any of the lines in your APT source-list files (see sources.list(5) (https://manpages.debian.org/buster//buster/apt/ sources.list.5.html) ) contain references to “stable”, this is     effectively pointing to buster already. This might not be what you want if you are not yet ready for the upgrade. If you have already run apt update, you can still get back without problems by following the procedure below. If you have also already installed packages from buster, there probably is not much point in installing packages from stretch     anymore. In that case you will have to decide for yourself whether you want to continue or not. It is possible to downgrade packages, but that is not covered here. As root, open the relevant APT source-list file (such as /etc/apt /sources.list) with your favorite editor, and check all lines     beginning with deb http:, deb https:, deb tor+http:, deb tor+https:, URIs: http:, URIs: https:, URIs: tor+http: or URIs: tor+https: for a reference to “stable”. If you find any, change stable to stretch. If you have any lines starting with deb file: or URIs: file:, you     will have to check for yourself if the location they refer to contains a stretch or buster archive. Important     Do not change any lines that begin with deb cdrom: or URIs: cdrom:. Doing so would invalidate the line and you would have to run apt-cdrom again. Do not be alarmed if a cdrom: source line refers to “unstable”. Although confusing, this is normal.     If you've made any changes, save the file and execute     # apt update     to refresh the package list. A.3. Removing obsolete configuration files Before upgrading your system to buster, it is recommended to     remove old configuration files (such as *.dpkg-{new,old} files under /etc) from the system. A.4. Upgrade legacy locales to UTF-8 Using a legacy non-UTF-8 locale has been unsupported by desktops and other mainstream software projects for a long time. Such     locales should be upgraded by running dpkg-reconfigure locales and selecting a UTF-8 default. You should also ensure that users are not overriding the default to use a legacy locale in their environment. Appendix B. Contributors to the Release Notes     Many people helped with the release notes, including, but not limited to Adam D. Barratt, Adam Di Carlo, Andreas Barth, Andrei Popescu, Anne Bezemer, Bob Hilliard, Charles Plessy, Christian Perrier, Christoph Berg, Daniel Baumann, David Prévot, Eddy Petrișor, Emmanuel Kasper, Esko Arajärvi, Frans Pop, Giovanni Rapagnani, Gordon Farquharson, Hideki Yamane, Holger Wansing, Javier Fernández-Sanguino Peña, Jens Seidel, Jonas Meurer, Jonathan     Nieder, Joost van Baal-Ilić, Josip Rodin, Julien Cristau, Justin B Rye, LaMont Jones, Luk Claes, Martin Michlmayr, Michael Biebl, Moritz Mühlenhoff, Niels Thykier, Noah Meyerhans, Noritada Kobayashi, Osamu Aoki, Paul Gevers, Peter Green, Rob Bradford, Samuel Thibault, Simon Bienlein, Simon Paillard, Stefan Fritsch, Steve Langasek, Steve McIntyre, Tobias Scherer, victory, Vincent McIntyre, and W. Martin Borgert.     This document has been translated into many languages. Many thanks to the translators! Index A Apache, What's new in the distribution? B BIND, What's new in the distribution? C Calligra, What's new in the distribution? Cryptsetup, What's new in the distribution? D DocBook XML, Sources for this document Dovecot, What's new in the distribution? E Evolution, What's new in the distribution? Exim, What's new in the distribution? G GCC, What's new in the distribution? GIMP, What's new in the distribution? GNOME, What's new in the distribution? GNUcash, What's new in the distribution? GnuPG, What's new in the distribution? I Inkscape, What's new in the distribution? K KDE, What's new in the distribution? L LibreOffice, What's new in the distribution? LXDE, What's new in the distribution? LXQt, What's new in the distribution? M MariaDB, What's new in the distribution? MATE, What's new in the distribution? N Nginx, What's new in the distribution? O OpenJDK, What's new in the distribution? OpenSSH, What's new in the distribution? P packages apparmor, AppArmor enabled per default apparmor-profiles-extra, AppArmor enabled per default apt, Contributing upgrade reports, Adding APT sources for a local mirror apt-listchanges, Minimal system upgrade aptitude, Checking APT configuration status, Make sure you have sufficient space for the upgrade, Purging removed packages cryptsetup, Cryptsetup defaults to on-disk LUKS2 format cups, Driverless printing with CUPS 2.2.10 cups-browsed, Driverless printing with CUPS 2.2.10 cups-filters, Driverless printing with CUPS 2.2.10 dblatex, Sources for this document debian-goodies, Make sure you have sufficient space for the upgrade debian-kernel-handbook, Installing a kernel metapackage debian-security-support, Limitations in security support dkim-milter-python, Deprecated components for buster dkimpy-milter, Deprecated components for buster doc-debian, Reporting bugs docbook-xsl, Sources for this document dpkg, Contributing upgrade reports ecryptfs-utils, Noteworthy obsolete packages evince, AppArmor enabled per default evolution, evolution-ews has been dropped, and email inboxes using Exchange, Office365 or Outlook server will be removed evolution-ews, evolution-ews has been dropped, and email inboxes using Exchange, Office365 or Outlook server will be removed fcitx, Some applications don't work in GNOME on Wayland gnome-control-center, Accessing GNOME Settings app without mouse gnome-disk-utility, gnome-disk-utility fails to change LUKS password causing permanent data loss (buster 10.0 only) grub-efi-amd64-signed, UEFI Secure Boot grub-efi-ia32-signed, UEFI Secure Boot haveged, Daemons fail to start or system appears to hang during boot how-can-i-help, Contributing to Debian icinga, Deprecated components for buster icinga2, Deprecated components for buster icinga2-classicui, Deprecated components for buster icingaweb2, Deprecated components for buster ifupdown, Migrating from legacy network interface names initramfs-tools, Debug shell during boot using initrd, Upgrading your kernel and related packages ipsec-tools, Noteworthy obsolete packages iptables, Network filtering based on nftables framework by default keepass2, Noteworthy obsolete packages libreswan, Noteworthy obsolete packages linux-image-*, Upgrading your kernel and related packages linux-image-amd64, Installing a kernel metapackage linux-source, Installing a kernel metapackage localepurge, Make sure you have sufficient space for the upgrade locales, Existing PostgreSQL databases need to be reindexed locales-all, Existing PostgreSQL databases need to be reindexed mailman, Deprecated components for buster mailman3, Deprecated components for buster mailman3-full, Deprecated components for buster manpages-de, Substantially improved man pages for German speaking users mcelog, Noteworthy obsolete packages mutt, Substantially improved man pages for German speaking users, mutt and neomutt neomutt, mutt and neomutt phpmyadmin, Noteworthy obsolete packages popularity-contest, Make sure you have sufficient space for the upgrade pyspf-milter, Deprecated components for buster python-2.7, Deprecated components for buster racoon, Noteworthy obsolete packages rasdaemon, Noteworthy obsolete packages release-notes, Reporting bugs on this document revelation, Noteworthy obsolete packages rpcbind, NIS server does not answer NIS client requests by default s3ql, S3QL URL changes for Amazon S3 buckets shim-signed, UEFI Secure Boot spf-milter-python, Deprecated components for buster sshd, sshd fails to authenticate ssmtp, Noteworthy obsolete packages synaptic, Checking APT configuration status, Some applications don't work in GNOME on Wayland systemd, Substantially improved man pages for German speaking users, Daemons fail to start or system appears to hang during boot, Module configuration for bonding and dummy interfaces tinc, Prepare a safe environment for the upgrade udev, Upgrading your kernel and related packages, Migrating from legacy network interface names unattended-upgrades, Unattended-upgrades for stable point releases upgrade-reports, Contributing upgrade reports usrmerge, Merged /usr on fresh installs util-linux, Substantially improved man pages for German speaking users xmlroff, Sources for this document xsltproc, Sources for this document ypbind, ypbind fails to start with -no-dbus Perl, What's new in the distribution? PHP, What's new in the distribution? Postfix, What's new in the distribution? PostgreSQL, What's new in the distribution? X Xfce, What's new in the distribution? Glossary ACPI Advanced Configuration and Power Interface ALSA Advanced Linux Sound Architecture BD Blu-ray Disc CD Compact Disc CD-ROM Compact Disc Read Only Memory DHCP Dynamic Host Configuration Protocol DLBD Dual Layer Blu-ray Disc DNS Domain Name System DVD Digital Versatile Disc GIMP GNU Image Manipulation Program GNU GNU's Not Unix GPG GNU Privacy Guard LDAP Lightweight Directory Access Protocol LSB Linux Standard Base LVM Logical Volume Manager MTA Mail Transport Agent NBD Network Block Device NFS Network File System NIC Network Interface Card NIS Network Information Service PHP PHP: Hypertext Preprocessor RAID Redundant Array of Independent Disks SATA Serial Advanced Technology Attachment SSL Secure Sockets Layer TLS Transport Layer Security UEFI Unified Extensible Firmware Interface USB Universal Serial Bus UUID Universally Unique Identifier WPA Wi-Fi Protected Access