There is a bug in some versions of Tunnelblick which can result in the error above shown in the logs. To resolve follow the steps below.
- Ensure that you are running the latest stable version of Tunnelblick.
- Click on the Tunnelblick menu bar icon and then VPN details. Select the server you are trying to connect to and click the advanced button. Change the option Load TUN driver automatically to Always load TUN driver.
- If neither of the above resolve the issue, restart your computer and try again.