SUMMARY It is impossible to clear the clipboard, was fully functional on 6.2.x, broken on the 6.3 beta (6.2.90). Trying to clear it logs the following to the journal: Jan 18 19:45:21 HOSTNAME plasmashell[1589]: qt.sql.qsqlquery: QSqlQuery::exec: database not open Jan 18 19:45:21 HOSTNAME plasmashell[1589]: org.kde.klipper: A transaction didn't start: "Driver not loaded Driver not loaded" STEPS TO REPRODUCE 1. copy something to the clipboard 2. try to clear the clipboard 3. clipboard stays filled OBSERVED RESULT Clipboard doesn't clear when one invokes the clear clipboard history action EXPECTED RESULT Clipboard clears when one invokes the clear clipboard history option Clipboard SOFTWARE/OS VERSIONS Linux Version: u2d ArchLinux running kernel 6.12.9-arch1-1 KDE Plasma Version: 6.2.90 KDE Frameworks Version: 6.10.0 Qt Version: qt6.9.0beta1-1 ADDITIONAL INFORMATION Another interesting thing to add is that clipboard history size is set to 1 as that is all I need, but yes since the clear invoke doesn't work it auto-overriding last copy with current copy doesn't work either which means that the history actually does get really really long on a long desktop session without being able to do anything about it.
Cannot reproduce with current git master and default settings? Are you using any non-default clipboard settings?
Did some more digging, and yeah it was fixed in commit https://invent.kde.org/plasma/plasma-workspace/-/commit/739d17b0fbbc50fea907c033d251906a611d237f Keeping "save clipboard history" on for now (as that does indeed fix the issue) as the 6.2.90 beta tarballs that arch kde-unstable builds from don't contain that commit yet, and will revert that configuration change of mine once 6.3 is actually out
Fantastic! Looks like this change is actually only in 6.4 (AKA git master right now), which is why I have it and you don't. I'll see if it can be backported.
I was wrong, it was backported in https://invent.kde.org/plasma/plasma-workspace/-/commit/357aa9cb1e309bd21aa405de5d1dd720a667821d