Hyper-V VM adapter as Unknown device

During my migration project, one of the Hyper-V hosts had a failure. The VHDX was imported to a different Hyper-V 2016 cluster and brought up successfully. But the VM network adapters were not showing up. Upon further digging, I found that the VM adapters were showing up as Unknown devices in the device manager.

After multiple VM restarts and re-adding the VM adapter it was still showing up as an unknown device. I even tried an auto-scan but it was unsuccessful. Upon searching on TechNet forums I came across this great blog post –  https://blogs.msdn.microsoft.com/jjameson/2011/03/14/removing-stale-network-adapters-in-hyper-v-vm/

set devmgr_show_nonpresent_devices=1
start devmgmt.msc

In the Device Manager window:

1. Click the View menu and then click Show hidden devices.
2. Expand Network adapters.
3. Right-click each network adapter that begins with Microsoft Virtual  Network Adapter and click Uninstall. When prompted to confirm the device uninstall, click OK.
4. Right-click Network adapters and then click Scan for hardware changes.
5. Restart the VM and insert Integration Disk if your Hypervisor is 2012/2012R2. 

But in my case, my Hyper-V server was Server 2016  which doesnot have an Integration disk. In 2016 the integration disk files are inside the Guest OS so I gave a search in the Windows folder.All the results were pointing to a WinSxS folder. So I did the below steps.

1. Right-click Unknown device and then click Locate and install drivers manually.
2. In the search location : C:\Windows\WinSxS

In seconds my VM adapter got detected and my virtual machine was back on the network.