An agent may report a "Database error" message for a job.
This error means that the database file (.db) from the agent's storage folder got damaged.
If this error pops up shortly after job creation, most possible reason is that the agent was not able to create the database file in the storage folder. Recheck the path availability and see if the agent has read-write system permission in the directory.
If the error appears in the course of using the job, the db file got malformed. To fix that, remove the agent from the group or the job (depending on the job type). At this point the database file shall get deleted. Add the agent back to the group or job so that new database got created.