reinstall the Tap driver
Check if it is already installed by opening C:\Program Files\TAP-Windows
Right click on Uninstall and select Run as administrator
Reboot the system (not required, but recommended)
Download the Tap driver from
https://swupdate.openvpn.org/community/releases/tap-windows-9.21.2.exe and install it (right click on it > Run as administrator)
原文：
https://vpn.ac/knowledgebase/64/OpenVPN-Error-All-TAP-Windows-adapters-on-this-system-are-currently-in-use.html
