Notifier-celery-workers Exited too quickly

notifier-celery-workers Exited too quickly
OperationalError: database is locked

As the error indicates, please check the access to your database. You can also look in /edx/var/log/supervisor/notifier-celery-workers-stderr.log file for more detailed error traceback.

I apologize my lack of knowledge.

Who can I test the access to the database?

Where is the lock file?

Thank you in advance