You shouldn't backup de VBR Server. We recommend create the configuration backup. This is enough to get everything working. 

Hi ​@wesmrt 

This because the VBR server is not dedicated only for VBR, but the server have another roles also.

Though Veeam doesn't recommend doing so, yes...it can be done. I back mine up & have been doing so for quite a long time with no issues. 

It looks like you may be trying to back yours up with an Agent? So I guess you have a physical server used for Veeam? Mine is virtual and always has been. So if you're having an issue using the Agent on a physical computer, I've not had experience there.

As we always suggest, you can either look at the log files for more info or contact Support. 

As mentioned configuration backup is the method for the VBR server but yes you can also back itself up as I also do it as well like Shane but my server is a VM.

Out of curiosity, what other role do you have installed?! 

Best practice is one role per server, so if you have VBR on a server, it really should be running only VBR.  There can be issues introduced where a snapshot is taken of the VBR server (assuming it’s a VM) while it’s taking a snapshot.  I think that primarily is if the VBR server is also being used as a proxy server such as in an all-in-one solution.  That said, if you must backup your VBR server, I’d recommend using the Veeam Agent for Windows and running an agent-level backup rather than an image-level, but the best best is to separate out whatever other role you have on this server as well.