Hyper V Failed to add device ‘Microsoft Synthetic Ethernet Port’

So just another quick one here, I encountered a server having huge issues modifying and creating VM’s. The issue was exasterbated by the fact the drive holding the VM’s had run out of space and they where all “saved” and offline. In any case after lots of investigating and attempting to fix the VM’s (after freeing space) I still couldn’t create or edit existing VM’s! The message poping up was something like this

The server encountered an error while configuring network on ——– Failed to add device ‘Microsoft Synthetic Ethernet Port’.

So the fix, at least for me, was Antivirus exclusions! The box in this case was running AVG enterprise and by adding an exclusion on the virtual machine directory the problem seen above went away, I have since heard of similar issues with other AV apps and also MS Forefront causing the same issues.

Hope this helps :)

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