"Unable to start the virtual device" (Windows 10)

Hyper-V

This error may be caused by Hyper-V which interferes with VirtualBox. Please make sure Hyper-V is disabled when using Genymotion Desktop. See Genymotion Desktop and Hyper-V (Windows 8/8.1/10) for instructions.

VPN

Also, VPNs interfere with Genymotion and VirtualBox. If you use a VPN, please read Genymotion Desktop and VPN for more details.

Windows Defender

The Memory Integrity Core Isolation feature of Windows Defender is known to cause this type of errors. Make sure it is disabled before using Genymotion Desktop. For more information, please refer to How to disable Memory integrity in Windows 10?

Other

If none of the above apply to you, please try the following:

1. Open Windows Settings > Network & Internet > Change adapter options
2. Right-click on VirtualBox Host-Only Ethernet Adapter
3. Select Disable
4. Right-click on the VirtualBox Host-Only Ethernet Adapter again and Select Enable

If you have several Host-only interface adapters, you need to repeat this to each of them.

If it still does not work, please try this:

1. Open Settings > Network & Internet > Change adapter options
2. Right-click on VirtualBox Host-Only Ethernet Adapter
3. Click on Properties and then Configure
4. Click on the Driver tab
5. Click on Update Driver
6. Select Browse my computer for drivers. Now choose Let me pick from a list of available drivers on my computer
7. Select VirtualBox Host-Only Ethernet Adapter from the list and click on Next
8. Click Close to finish the update

If none of the above works, try to remove and re-install VirtualBox.