Problem
The upgrade to UCS 4.3-1 fails and you see messages like this in the file /var/log/univention/updater.log:
W: GPG-Fehler: https://updates.software-univention.de/3.2/maintained/component transition/all/ Release: Die folgenden Signaturen waren ungültig: EXPKEYSIG 1DD67AFB2CBDA4B0 Univention Corporate Server 3.x Archive Key <packages@univention.de>
You might see a similar error message regarding a different repository like this:
W: GPG-Fehler: https://updates.software-univention.de/3.2/unmaintained/component 3.2-5-errata/amd64/ Release: Die folgenden Signaturen waren ungültig: EXPKEYSIG 1DD67AFB2CBDA4B0 Univention Corporate Server 3.x Archive Key <packages@univention.de>```
Solution
Disable the outdated repository and clean local cached data. Additionally if you see the second error please disable you unmaintained repository first.
ucr set repository/online/unmaintained=no
ucr set repository/online/component/transition=disabled
apt clean
apt update