Just to be of help to anyone who’s looking for a fix using their own scripts. You can add the following command to your init script to add the variable:
export XDG_CONFIG_HOME="/some/path/"
This command should be somewhere before ‘run_rc_command’.
Note that ‘/some/path/’ should be writable for the user that’s running Sonarr.
This will fix the issues with the GUI not updating and allows SignalR to run as it should.