ORA-01089 is just a warning that the DB is being shut down.
If a job is about to be spawned when shutdown of database is in progress, you will see these errors in the alert log file and this is perfectly valid.
There is no harm at all because of this warning being logged to the alert.log The Error can be safely ignored as the job coordinator process tried to spawn a job slave when the Shutdown was in progress.
One workaround that we can suggest is to set an underscore parameter
_JOB_QUEUE_INTERVAL=120 or greater value
The default value is 60 but when we change to 120 there are less chances of getting the above warnings in the alert log file.
More Information: (MOS) : Kkjcre1p: Unable To Spawn Jobq Slave Process, Error 1089 (Doc ID 344275.1)