I fixed it! 
Solution:
Make a backup in Sonarr and store the backup in a safe location. ^^
1. Stop the sonarr service:
sudo service nzbdrone stop
2. Remove everything in this folder: (It’s the location of the AppData directory for Sonarr)
/home/pi/.config/NzbDrone
3. Restore the files from the backup (Two files, nzbdrone.db and config.xml)
/home/pi/.config/NzbDrone
4. Restart the service
sudo service nzbdrone start
5. Update sonarr