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 or open 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 following error appears in the course of using the job, the db file got malformed.
How to resolve this error?
As a first step, restart the agent which reports the issue.
If it doesn't help - remove the agent from the group or the job (depending on the job type), then add the agent back to the group or job; or use "Restart on agents" button in the job run. This causes the agent to delete the database and create it again from scratch.