Backup, file manipulation operations (such as ALTER DATABASE ADD FILE) and encryption changes on a database must be serialized.

You might have come across this error in some of the occasion.

"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."

You might get this error when one of your Backup Job fails or Shrink Database Job fails or while you are taking a backup manually or shrinking a database manually etc.

Ever wondered what is this and what caused this error?

The Error itself says all. "Backup, File Manipulation Operations and Encryption changes on a database must be serialized". So what does this mean? This means these operations cannot be run parallely. I.e, when a backup for database is running you cannot shrink the same database at same time or try to add a data file or try to make encryption changes.

A simple solution to this is Make sure you wont overlap the Serialized operations such as Backup database, Shrink Database etc.

Schedule your jobs in such a way that these operations such as Backup Database, Shrink Database etc run one after the other not parallely or simultenously.

Hope this information was helpful.