In general, the SQL Server error message above indicates a permission issue on the database side. The given database user for the connection is not allowed to access the given database.
However, this article addresses the following specific error situation:
- Frontends are working
- Job service loads jobs normally and tries to process them
- Many of these jobs fail with the given error message which can be seen in the ErrorMessages field in the table jobqueue
In this particular instance, the cause for the error is an incorrect ConnectionString in DialogDatabase. Any jobs where the task has a ConnectionString parameter will copy the incorrect information from DialogDatabase into the job parameter during job generation.