Occasionally (perhaps when rebooting the home PC in a hurry) the previous openvpn connection doesn’t get closed down properly. When trying to reconnect openvpn declares that the required UDP socket is already being used.
To solve this, find the pid of the previous connection:
markp@markp-study:~$ ps aux | grep openvpn
markp 5507 0.0 0.0 3240 800 pts/2 S+ 17:47 0:00 grep openvpn
root 6889 0.0 0.1 5132 3060 ? S Oct05 2:38 openvpn –config XXXXX.ovpn
Kill that process:
markp@markp-study-home:~$ sudo kill -KILL 6889
Should fire up OK after that!