When you restore a previous registry using the scanreg /restore command, you may receive the following error message:
Microsoft Registry Checker
System restore operation failed.
This behavior occurs because you are attempting to restore the oldest version of the saved registries. The maximum number of registries is already saved as specified in the Scanreg.ini file by the MaxBackupCopies setting.
When you attempt to restore the oldest registry, Windows attempts to back up the current registry. Because Windows attempts to overwrite the same registry backup that you are attempting to restore, the restore operation is unsuccessful.
NOTE: Your oldest registry backup is still replaced with a backup of the current registry, and the oldest registry is no longer available to restore.
To resolve this issue, perform either of the following actions before using the scanreg /restore command:
Rename one or more of the other saved registry backups to make room for another backup.
Increase the MaxBackupCopies setting in the Scanreg.ini file to accommodate a backup of the current registry.
You can also manually restore the registry files, which prevents the automatic backup of the current registry. For more information about this option, click the article number below to view the article in the Microsoft Knowledge Base:
220878 Error Message: Restore Operation Failed