Unable to register the machine. Unable to backup or schedule a backup. All operations are failing.
This error occures when is a time skew between the server being registered and the actual time. This could have happened because the timezone has been set wrong. This could also have happened if the time is set too far in past or future
Check if Windows Time service is running on the machine. Then use the following steps to either restart or run the Windows Time service on the machine.
The timezone or time can also be set manually through Change date and time settings ...