After reading about the possibility to Live Migrate between versions and now getting the R2 bits I had to test the migration of a VM from a Hyper-V 2012 enabled host to a newly installed Hyper-V 2012 R2. I have on both the hosts enabled the migration on the hosts with kerberos authentication and also set up delegation.

When starting a migration I got the following error, and it did not tell me what was actually wrong, but after I disconnected the ISO that was connected the migration succeeded nicely!

So here is a perfect place for you to check your VM´s for connected ISO´s and disconnect them before migrating and that can easily be done with PowerShell,

Get-VM -ComputerName HV01 | Get-VMDvdDrive | where DVDMediaType -ne None | Set-VMDvdDrive -Path $null

After this has been done I can continue to migrate the server and that can also be done with PowerShell,

Move-VM -ComputerName hv01 -Name win2k3-01 -DestinationHost hvr2 -IncludeStorage -DestinationStoragePath c:\vms\win2k3-01

As you can see it now resides on the 2012 R2 server and is still running :-).

When trying to migrate the VM back to the 2012 Hyper-V I get an strange error (yes I know, it is not supported but I had to try!), the error message could have been a bit more informative, and I have tested to set the migration option to just TCP/IP instead of compression but still get the same error message!

And with powershell I get a bit clearer view of the error message,