After upgrading to Windows 10 from Windows 7, I ran into an issue with VirtualBox (version 5.0.0r101573) and my virtual machines. None of them would boot up. After looking in the VirtualBox preferences (not Settings for each VM), I discovered my host-only adapters were completely gone. Figuring the upgrade removed these drivers from the system, I would simply add them back and move along. No big deal, right? Wrong.
When I attempted to add a new host-only adapter, VirtualBox gave me the error:
Failed to create the host network interface.
After some googling, people were suggesting the ol' uninstall VirtualBox, restart, re-install VirtualBox, restart routine. And according to them, this worked (at least for Windows 8/8.1). There were a few other hacks people suggested and claim to work for them, but nothing was working for me.
Compatibility Mode to the rescue!
Thinking it worked with Windows 7 and the nice Compatibility mode feature, I would give that a try.
1. Open the VirtualBox.exe file location and right click and choose `Properties`.
2. Click the `Compatibility` Tab and choose `Windows 7` under Compatibility Mode; and also check `Run this program as administrator`.
3. Click Apply and OK
Perhaps there are other ways of fixing this, but this worked for me.