Ghost 14 Error message EC8F1C5

Have recently changed the backup destination to a new SATA drive. The weekly backup of the entire boot disk runs without incident. The daily backup of selected folders ends with:

 

       "Error EC8F1C50: Cannot create file backup for job: docNset. Error E4BC0012: An interaction with the catalog's

      database layer failed unexpectedly: sqlite3_step--5: database is locked.
      Details: 0xE4BC0012
      Source: Norton Ghost"

 

Can't find a reference to this error. Have removed and recreated the backup task - into a different folder on the SATA drive. Same error