My digikam program stopped working on my Debian desktop and finally I found out why. I always got the following error message:
QSqlDatabasePrivate removeDatabase connection ConnectionTest is still in use all queries will cease to work
I googled around and did not find any hint on what was going on. So when looking at the STackstrace in drKonqi I saw that the crash was actually triggered in libmarble. I updated libmarble manually - and voila: now it works again.
There seem to be some dependencies missing.