Msg 4212, Level 16, State 1, Line 2
Cannot back up the log of the master database. Use BACKUP DATABASE instead.
This error message appears when you try to backup the log of the master database.
The T-SQL statement can be parsed, but causes the error at runtime.
Error of the Severity Level 16 are generated by the user and can be fixed by the SQL Server user. The log of the master database cannot be backed up. Rather you should backup the master database itself in regular intervals.
All versions of SQL Server
BACKUP LOG master TO DISK = ‘D:Datamaster_log.bak’
By default the master database is in simple recovery mode. Although you can due to backward compatibility issues run the master database in different recovery mode than simple, it behaves as if it is in simple recovery mode. BACKUP LOG cannot be used against the master database.