AKA Schrödinger’s Backup. Until you have successfully restored from a backup, it is just an amorphous blob of data that may or may not be valid.

I say this as someone who has had backups silently fail. For instance, just yesterday, I had a managed network switch generate an invalid config file for itself. I was making a change on the switch, and saved a backup of the existing settings before changing anything. That way I could easily reset the switch to default and push the old settings to it, if the changes I made broke things. Sure enough, the change I made broke something, so I performed a factory reset and went to upload that backup I had saved like 20 minutes prior… When I tried to restore settings after the factory reset, the switch couldn’t read the file that it had generated like 20 minutes earlier.

So I was stuck manually restoring the switch’s settings, and what should have been a quick 2 minute “hold the reset button and push the settings file once it has rebooted” job turned into a 45 minute long game of “find the difference between these two photos” for every single page in the settings.