Ubuntu to Fix A 20 Years Old Bug by Removing /etc/debian_version
Ubuntu is finally going to remove the /etc/debian_version file to close a bug that was reported almost 21 years ago on July 31, 2005.
The Debian and Ubuntu developer, Benjamin Drung, announced the decision on Ubuntu Devel channel:
Hi everyone, any objection to remove /etc/debian_version from base-files? /etc/os-release has been the de-facto standard in the last 10 years. Tools that look at /etc/debian_version should look at /etc/os-release instead.
Please let me close this bug after 20 years:
https://bugs.launchpad.net/ubuntu/+source/base-files/+bug/19353
What is /etc/debian_version file
The /etc/debian_version file from base-files package tells which version of Debian package base that the current Ubuntu system is based on.
As Ubuntu (during the development) mostly imports Debian packages from its Unstable branch (code-name sid), and, Debian Unstable is the development branch from which the next stable release is prepared. The file content usually looks like bookworm/sid, trixie/sid, or forky/sid.
For Ubuntu 26.04, /etc/debian_version file contains forky/sid, meaning the system is associated with Debian Unstable (sid) in the period that Debian 14 (forky) are prepared.
The file is mainly intended for scripts and programs to detect Debian-based system or check which Debian release the system is compatible with.
Why to remove the file?
As the Ubuntu developer announced, scripts and programs should look at /etc/os-release file, which has been the de-facto standard in the last 10 years, instead of /etc/debian_version. And, due to the favor of /etc/os-release, most recent build of base-files has removed /etc/lsb-release.
As Ubuntu has been one of the top popular Linux Distributions and it also includes so many libraries that are not available in Debian, most Linux programs now provide Ubuntu support without needing to know which version of Debian it’s based on.
If you have some tools that are still looking to /etc/debian_version file, then you may now ask developers to update, as the file will be possibly removed in the next Ubuntu 26.10.
Source: UbuntuHandbook