You can use File Browser to restore backups when your Arr apps complain about malformed databases!
Many apps will create regular, scheduled backups.
Before you restore, uninstall the app via your account, to avoid any conflict re the restored files.
Next, in File Browser, navigate to
/config/<app>/.migrated-to-tmpfs. These are copies of the (corrupt) database stored in the event of an unhealthy pod shutdown. Delete the contents of
/config/<app>/.migrate-to-tmpfs (else the corrupted files will just be restored on the next app start).
/config/<app>/Backups, identify and the most recent backup by sorting the files by date:
Download and unpack the backup locally, then navigate to the root of the app's directory in
/config/<app>, and upload the unpacked backup files:
You'll be prompted to overwrite the existing files (this indicates that you're restoring to the correct directory)
Finally, install the app again via your account