You should check if you did everything like described in the howto installation guide: https://hashcat.net/wiki/doku.php?id=linux_server_howto
The main problem might be that you didn't run:
$ xhost +
in a session where X11 is running (for instance not over ssh).
You should add that command as suggested in the guide to the startup s.t. you don't need to run it manually each and every time.
The main problem might be that you didn't run:
$ xhost +
in a session where X11 is running (for instance not over ssh).
You should add that command as suggested in the guide to the startup s.t. you don't need to run it manually each and every time.