SQL Server BACKUP stop_on_error parameter

Question

When using the stop_on_error parameter in SQL Server, what actually happens if you overwrite an existing file *.bak?

Will it be stopped before overwriting an existing valid backup or ruining a valid existing backup and then stopping the operation?

The official documentation does not explain this in detail.

Answer 1

Speaking from experience, a few weeks ago I redefined the existing backup file (there was no free space), and the backup failed 99% (!). SQL2008. The size of the bak source file did not change, but when I tried to restore it, it gave an error that “the backup header was damaged” and the restore failed. I'm not sure if this always happens, but from now on - I make a backup in another file and switch after a successful backup check.