I'm getting mixed information from the forum and knowledge base. 

I successfully installed Physical Backup Server on a physical 2008 R2 server. It backed up successfully without issue. 

I then tried to restore it to a VM on a Hyper -V host, and it failed with this error:

Restoring from a Windows Server 2008 R2 machine is not supported.  (Error code RestoringFromWin2008R2NotSupported)

To clarify, the error is specifically about restoring FROM a Windows Server 2008 R2 machine:

Restoring from a Windows Server 2008 R2 machine is not supported.  (Error code RestoringFromWin2008R2NotSupported)

I tried restoring TO the following FROM the WIndows Server 2008 R2 Physical Host that I backed up:

• I have a 3-node 2012 R2 Hyper-V Failover Cluster writing to a SAN, and the restore fails. 
• I have a 1-node 2012 R2 Hyper-V Failover Cluster writing to a SAN, and the restore fails.
• I have a standalone 2012 R2 Hyper-V host writing to local storage, and the restore fails.
• I have a standalone 2016 Hyper-V host writing to local storage, and the restore fails.

In all cases, I get the error restoring FROM 2008 R2.

I will contact support directly.

I think that the missing piece is that the Restore process cannot be RUN ON a 2008 R2 machine.

My interpretation of the workflow was to install the Altaro Physical Backup software ON a 2008 R2 machine, back up that machine to an onsite location, then use that same software ON that same 2008 R2 machine to restore the backup as a VM or VHD TO a 2012 R2 host. This appears to not be the case.

To make this work, it appears that I will need to additionally install the Altaro Physical Backup software on a 2012 R2 VM host in addition to the 2008 R2 machine I backed up. And then initiate the Restore ON the 2012 R2 host FROM the onsite backup location