BigSur and Tunnelblick VPN client – Cannot allocate TUN/TAP dev dynamically

BigSur and Tunnelblick VPN client – Cannot allocate TUN/TAP dev dynamically

When running on macOS Big Sur 11.0.1 or later, Tunnelblick forces the settings on Tunnelblick’s „Advanced“ settings window to „never load“ system extensions. (The developers plan to release a version of Tunnelblick which will be „smarter“ about this.) 

• 2021-01-29 08:37:12.201142 MANAGEMENT: Client disconnected
• 2021-01-29 08:37:12.201217 Cannot allocate TUN/TAP dev dynamically
• 2021-01-29 08:37:12.201281 Exiting due to fatal error
• 2021-01-29 08:37:13.766778 *Tunnelblick: Expected disconnection occurred.

You can override that behavior and allow the settings to act normally by executing the following command in Terminal:

defaults write net.tunnelblick.tunnelblick bigSurCanLoadKexts -bool yes

The override can be removed by executing:

defaults delete net.tunnelblick.tunnelblick bigSurCanLoadKexts