Debian 11 has been released. Along with this, the repositories of Debian 10 were changed from “stable” to “oldstable“.
If you try to do an apt-get update on the server now, there is an error:
root@vps:/# apt-get update Get:1 http://deb.debian.org/debian buster InRelease [122 kB] Reading package lists... Done N: Repository 'http://deb.debian.org/debian buster InRelease' changed its 'Version' value from '10.9' to '10.10' E: Repository 'http://deb.debian.org/debian buster InRelease' changed its 'Suite' value from 'stable' to 'oldstable' N: This must be accepted explicitly before updates for this repository can be applied. See apt-secure(8) manpage for details.
The fact that the suite value has been changed must be explicitly confirmed. A single command is sufficient for this:
apt-get --allow-releaseinfo-change update
With this command we tell apt that the change has been accepted.
Now apt-get update, upgrade and install can be used again as usual.