Error : Geany tried to access the Unix Domain socket of another instance running as another user

If you get the following error when trying to launch Geany :

(geany:12755): Geany-WARNING **: Geany tried to access the Unix Domain socket of another instance running as another user.
This is a fatal error and Geany will now quit.

the solution is quite simple. Open a terminal and execute the following command:

$ rm .config/geany/geany_socket*

Now you can launch Geany without errors!