Adrian Buckman shows the types of errors you should expect when your default backup location is invalid:
Recently I was looking through the error log on one of my test machines and I spotted some unusual errors:
SQL ERROR: 3634 – The operating system returned the error ‘3(The system cannot find the path specified.)’ while attempting ‘DeleteFile’
SQL ERROR: 18272 – During restore restart, an I/O error occurred on checkpoint file (operating system error (null)). The statement is proceeding but cannot be restarted. Ensure that a valid storage location exists for the checkpoint file.
At first I assumed that I may have tried restoring a database to a location that did not exist but this was not the case, the actual issue was with SQL Server’s Default Backup Location.
Read on for the full explanation.