I switched to Deluge and it works, so probably the problem was Transmission (I don’t know how, I haven’t updated anything since the last time it worked). I don’t like Deluge, but if there aren’t alternatives… Donwload Station doesn’t work too.
Anyway I have another problem right now, when I try to create a backup Sonarr tells me
[backup] Failed
Do I have to open a new topic?