I've been getting this for a few days.
Failed to back up to
gs://{bucket}/{filename}.gz: An unknown problem occurred (ERROR_RDBMS)
The data bucket I'm usin gand filename are valid.
That's all the detail google is giving me. I see some other posts with this issue but someone (I assume from google) always says he will help them and notify them offline.
I've tried restarting the database instance.
thanks,