Differential backup of master database?

Someone posted a question yesterday. “Is it possible to take the differential backup of master database?”. The answer is No. Why not try taking the differential backup of master database instead. Open SSMS and the backup option looks like this.

Only FULL backup type is listed. So SQL Server does not allow any other type of backup operation to be performed on master database. Let us try out the script to take the differential backup of master database.

Here as well SQL Server states the same. You can only perform a full backup of the master database. It is confirmed that SQL Server is designed to allow only FULL backup of master database.

But why? For differential backups to be applied on a database, the database has to be in NORECOVERY (Recovering) state. But SQL Server does not allow master database to be restored without recovery. Master database has to be in Recovered status always.

Moral of the story is you can only take FULL backup of master database.