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Upgrade Debian 10 to Debian 11


In this article, we will describe the process of upgrading the OS from Debian 10 to Debian 11.



Before upgrading the operating system, we strongly recommend making a full backup of all data on the server. This will serve as an insurance policy in case of problems, allowing you to restore the system in the event of an emergency.


All commands during OS upgrade are executed in the server terminal under the root user.

Refuse system suggestions to replace configuration files (default action).

The names of repository files in /etc/apt/sources.list.d of your OS may be different from those used in these instructions.

  1. Make sure you have the correct repositories in /etc/apt/sources.list . The list of repositories for Debian 9 can be found below.
Debian 10 repositories
deb buster main contrib non-free
deb-src buster main contrib non-free

deb buster-updates main contrib non-free
deb-src buster-updates main contrib non-free

deb buster/updates main contrib non-free
deb-src buster/updates main contrib non-free
  1. Update all current packages to the latest versions
apt update && apt dist-upgrade
  1. Replace the list of repositories in /etc/apt/sources.list to those from Debian 11. The list of repositories for Debian 11 can be found below.
Debian 11 repositories
deb bullseye main contrib non-free
deb-src bullseye main contrib non-free

deb bullseye-updates main contrib non-free
deb-src bullseye-updates main contrib non-free

deb bullseye-security main contrib non-free
deb-src bullseye-security main contrib non-free
  1. Resolve potential proftpd update errors
sed -e 's/^IdentLookups/#IdentLookups/' -i /etc/proftpd/proftpd.conf
  1. Update packages. Run the following commands one at a time
apt update
apt upgrade
apt dist-upgrade
  1. Update other repositories
sed -i 's|buster|bullseye|g' /etc/apt/sources.list.d/*.list
  1. Add nginx repository keys
wget -q -O - |apt-key add -

The Debian 11 repository does not have older versions of the database servers. To upgrade further, you need to specify versions 8.0 and 10.5 for MySQL and MariaDB respectively in /etc/apt/sources.list.d/. You can find out the current database server version by executing the command

mysql -V

If MySQL is used, change the package version and add the repository key:

sed -i 's/mysql-5.7/mysql-8.0/g' /etc/apt/sources.list.d/mysql.list
wget -q -O - |apt-key add -

For MariaDB <10.5 use:

sed -i 's/10.[0-4]/10.9/' /etc/apt/sources.list.d/mariadb.list
  1. Update packages
apt update
apt dist-upgrade
  1. Install PHP 7.3 with base modules, PHP7.3-FPM and the Apache2 module
dpkg -l | awk '/php7.3/ {print $2}' | sed -e 's/7.3/7.4/'  | xargs apt install -y

apt install -f php php-fpm libapache2-mod-php libapache2-mod-php7.4 php-common php7.4-cgi php7.4-cli php7.4-common php7.4-curl php7.4-gd php7.4-json php7.4-mbstring php7.4-mysql php7.4-opcache php7.4-readline php7.4-xml php7.4-xmlrpc php-imagick php-memcached

phpenmod calendar ctype curl dom exif fileinfo ftp gd gettext iconv json mbstring mysqli mysqlnd pdo pdo_mysql phar posix readline shmop simplexml sockets sysvmsg sysvsem sysvshm tokenizer wddx xml xmlreader xmlrpc xmlwriter xsl opcache imagick memcached
  1. Replace PHP-FPM configurations
mv /opt/php74/etc/php-fpm.d/* /etc/php/7.4/fpm/pool.d/

rm /etc/php/7.3/fpm/pool.d/www.conf

mv /etc/php/7.3/fpm/pool.d/* /opt/php73/etc/php-fpm.d/
  1. Remove PHP 7.3
apt purge php7.3*
  1. Activate PHP 7.4
a2enmod php7.4
  1. Correct PHP version in FASTPANEL base
sqlite3 /usr/local/fastpanel2/app/db/fastpanel2.db "update site set php_version = 74 where mode = 'mpm_itk';"
  1. Reconfigure services
mogwai services configure -f
  1. Additional configuration depending on the database server used

For MySQL 8 - add compatibility settings

echo 'disable-log-bin
mysqlx = OFF
default-authentication-plugin = mysql_native_password
character-set-server = utf8
collation-server = utf8_unicode_ci
' >> /etc/mysql/my.cnf.fastpanel/99-fastpanel.cnf

For MariaDB - run mysql_upgrade

  1. Restart the server
  1. Make sure that all services are started after reboot
systemctl --failed

Upgrade complete.