[devkid]

Thanks for fast reply. The full log was included in the post (contains only the IMDB update though):
https://pastebin.com/Ri7wj394

I am using a MariaDB server as database and I could not reproduce the problem on my main player connected to the TV. So you could consider it solved.
Regarding the problem: the log was from my regular PC (it only happens there). Maybe the error happened cause my PC is using the MariaDB but it has no configured sources itself. So maybe it is a problem that it iterates over the database but cannot access the actual data since it has not sources?