Upgrade Debian 10 Buster to Debian 11 Bullseye

This guide explains how to upgrade your Debian Linux system from Debian 10 (Buster) to Debian 11 (Bullseye) which is now the current stable release as of August 14th, 2021.

These steps can be preformed as an in place upgrade on a live system from either a local terminal or remote SSH session.

Step 1

Prior to upgrading, make sure the current system is up-to-date.

apt update && apt upgrade

Step 2

Switch the Debian repositories from Buster to Bullseye by editing the source file.

vi /etc/apt/sources.list

Replace all instances of buster with bullseye. Then modify the security lines, replacing buster/updates with bullseye-security.

Current source.list should look similar to this:

deb http://deb.debian.org/debian buster main
deb-src http://deb.debian.org/debian buster main

deb http://deb.debian.org/debian-security/ buster/updates main
deb-src http://deb.debian.org/debian-security/ buster/updates main

deb http://deb.debian.org/debian buster-updates main
deb-src http://deb.debian.org/debian buster-updates main

Modified source.list will look like this once you're done:

deb http://deb.debian.org/debian bullseye main
deb-src http://deb.debian.org/debian bullseye main

deb http://deb.debian.org/debian-security/ bullseye-security main
deb-src http://deb.debian.org/debian-security/ bullseye-security main

deb http://deb.debian.org/debian bullseye-updates main
deb-src http://deb.debian.org/debian bullseye-updates main

If you also need the contrib and non-free components, add contrib non-free after main on all lines.

Debian is distributed (mirrored) on hundreds of servers worldwide. In our source.list example above we've used a repository within the United States, to speed up downloads you may choose another Debian mirror based on geographic location.

Third-party software installed from a repository will be disabled during the upgrade process. This may not apply to your system, so before starting, check for repository .list files within the /etc/apt/sources.list.d/ directory. If present, you'll need to update these after the upgrade. Consult the software distributor for instructions, as software from outside the standard Debian repositories may not support the new release.

Step 3

Update the package index.

apt update

Step 4

Upgrade the minimal base system.

apt upgrade

Step 5

Upgrade all other packages and dependencies.

apt dist-upgrade

Step 6

Reboot the system.

reboot

Step 7

Verify your release has been upgraded.

lsb_release -a

Output will be similar to this.

No LSB modules are available.
Distributor ID: Debian
Description: Debian GNU/Linux 11 (bullseye)
Release: 11
Codename: bullseye

Step 8

Clear out the local repository of retrieved package files and dependencies that are no longer required.

apt clean

apt autoremove