how do you move a VM from hyper-v 2012 R2 to hyper-v 2008 R2?

There are issues of incompatibility if you just try to export/import the VM, and for making it work you will need to make annoying modifications on the VM xml files. Better try shutting down the VM on WS2012 R2, then copy 'all' its files manually(VM files, VHD files, etc), put them somewhere in your 2008 R2 server and import the VM there.

Be aware that there are many scenarios where it is not going to work. For example if you were using VHDX virtual disks or Generation 2 VMs in Windows server 2012 R2, 2008 is not going to know what is that about. Additionally WS2008 R2 uses an older version of the integration services.

Extra Note: take in consideration that much more benefits of HyperV are over 2012 R2. If you can figure out how to virtualize all your VMs using WS2012 R2 it will be much more convenient for you.

schnellsolutions  : the VM i'm trying to move is VHDX format - its a management server so i need to move it to a Hyper v where there is more resources available .

So the bottom line is ....it can't be done?

You can make the process longer and convert the .VHDX virtual disk to .VHD

You can make it from the WS2012 HyperV server using powershell with the following command:

Convert-VHD   –Path   <VHDXLocationPath>.vhdx   –DestinationPath   <NewVHDLocation>.vhd

If you are using snapshots, merge the snapshots into the vhdx first from the HyperV Console.

There are other methods for converting the disk as well, but this is maybe the simplest one.

HyperV host has been upgraded