Recently a backup job was created to backup and VM from an ESXi host to a backup repository on a QNAP. Everything appeared to be configured correctly and all usernames and passwords were correct but it would still fail every time it was tested.
This is the error message I would see each time.
The network path was not found. Agent failed to process method {Stg.OpenReadWrite}.
After testing and removing and adding almost every part of the configuration again I finally figured out what the issue was. The credentials for the QNAP shared were correct but for some reason when I removed them from the credential manager and added them again the backup worked.
I have no idea why this worked because when I would choose the backup repository to use it could see used and free space details along with existing backups. The backup is now running without issue so it’s worth a try if you are having a similar issue.