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After migrating a virtual machine from another hypervisor (such as VMware or VirtualBox) to Hyper-V, you may notice that the network adapter is missing at the VM level.

In some cases, the network adapter does not appear in Device Manager and is instead listed as an unknown device.
When attempting to manually install the driver for the unknown device, you may encounter the error:

The system cannot find the file specified

Cause

This issue typically occurs because the required driver file netvsc.sys is missing from the following directory:
C:\Windows\INF

Solution

To resolve this issue, follow these steps:

1. Navigate to: C:\Windows\System32\DriverStore\FileRepository
2. Locate the folder containing the netvsc.sys file.
3. Copy the file to: C:\Windows\INF
4. Open Device Manager and reinstall the network adapter driver.

After completing these steps, the network adapter should be detected and function correctly in Hyper-V.

The log is located in C:\Windows\INF\setupapi.dev.log.