E: Release file for http://security.debian.org/debian-security/dists/bullseye-security/InRelease is expired (invalid since 3d 19h 29min 31s). Updates for this repository will not be applied.
What should i do next if i don’t want to reinstall/upgrade to 12?
My concerns are things breaking if i attempt an upgrade.
LTS support for Debian 11 ended on 2026-08-31. You should upgrade to Debian 12 or accept the risks of using an unsupported OS.
Any tutorial on upgrading safely from 11 → 12 ? I checked documentation and it looks messy there is only 1 small section for 11->12
No, I don’t have any tutorial but you could take a look to the doc for upgrading Debian 12 to 13 and use it as a base.
Also, if you are using sieve, antivirus and/or spam you will need to edit exim conf.
ps I envy you, it’s been such a long time since I had old OS’s around…
I only had 1 box that was on Debian 11, at that time our retarded provider did not have Debian 12 for this region (not sure why) because all our other deployments at that time was 12. Anyway i already upgraded to 12 and everything seems to be working okay.
I have had nothing but great experiences jumping up versions with Debian, glad of it, things didn’t used to be so easy!