How to troubleshoot Alter Database Failed SQLSTATE 42000 Error 3023

Question: I received an alert  for a regular backup failure . A closer inspection of the sql server agent error logs  displayed this error message: 

Executed as user: myUser. Backup, file manipulation operations (such as ALTER DATABASE ADD FILE) and encryption changes on a database must be serialized. Reissue the statement after the current backup or file manipulation operation is completed. [SQLSTATE 42000] (Error 3023) BACKUP DATABASE is terminating abnormally. [SQLSTATE 42000] (Error 3013). 

Answer: There are different reasons this error message is generated. The error message says that "ALTER DATABASE ADD FILE  and encryption changes must be serialized". This means there are some restrictions (or rules) defining what activity can take place when a full back is in progress. 

For example:

Only one backup operation can occur on a database at any time

Restriction on adding or dropping files on a database 

Restriction on database shrink if a database is being backed up

The first step in troubleshooting is to identify the other activity which is causing the error.  Check SQL Server Agent Jobs, and any other schedulers which may be triggering jobs conflicting with the backup. 

Also , check any other current activity which a user may be attempting.

Sometimes the problem may be generated indirectly. Let's say there is a failed backup being rerun - this backup may run unexpectedly into a window for another activity. SQL Server maintains a  Backup history for a single SQL Server database use the information out of the backup duration to assess whether the backup took longer than normal or was rerun .