Tunnelblick stores usernames and passwords in the macOS keychain. If you have recently updated your password and are having authentication failures then you should first delete the keychain entries:
- Open keychain access utility by navigating to your Applications folder and then Utilities.
- Select Login under keychains and all elements under Category.
- In the search box in the top right, enter tunnelblick to filter all the tunnelblick keychain entries.
- Select all the tunnelblick entries, select edit | delete.
- Close tunnelblick and open it again and try to connect.
If you continue to have authentication issues please see My VPN password doesn't work (authentication failure). What can I do?