Here are some steps you can take to resolve this issue:
Install TAP-Windows driver: OpenVPN relies on the TAP-Windows driver to create TAP adapters. You can download and install the TAP-Windows driver from the OpenVPN website (https://openvpn.net/index.php/open-source/downloads.html). Make sure to download the correct version that matches your operating system.
Enable TAP adapter in Network Connections: After installing the TAP-Windows driver, go to your system's Network Connections settings. Look for the TAP adapter, which is typically named something like "Local Area Connection" or "Ethernet." If you see the adapter, right-click on it and choose "Enable" or "Connect." If the adapter is not present, proceed to the next step.
Reinstall OpenVPN: Sometimes, a fresh installation of OpenVPN can help resolve issues with TAP adapters. Uninstall OpenVPN from your system, restart your computer, and then reinstall the latest version of OpenVPN. During the installation process, make sure to select the option to install the TAP-Windows driver.
Manually install TAP adapter: If the above steps don't work, you can try manually installing the TAP adapter. Open the OpenVPN installation directory (usually located in "C:\Program Files\OpenVPN"). Look for a folder named "driver" or "tap-windows" and navigate to it. Inside the folder, you should find an executable file with a .exe extension, such as "addtap.exe" or "tapinstall.exe." Run this file as an administrator to install the TAP adapter.
Check for conflicting software: Some security software or virtualization software, such as VMware or VirtualBox, can interfere with the installation or functionality of TAP adapters. Temporarily disable or uninstall such software to see if it resolves the issue.