Hi,

Following this workaround :
https://wiki.x2go.org/doku.php/wiki:development:glx-xlib-workaround did
the trick !

The workaround also works for ubuntu 18.04. I just replaced "aptitude"
by "apt".

I had to chown -R <me>:<me> mesa-18.0.5/ to be able to compile.

Now modifying nextcloud client launch sequence !

Cheers,

Thierry