fman does not start -X11 error

Hi,
I have followed your installation instructions for Ubuntu and if I just start fman, nothing happens, sometimes the screen flashes a bit.

/opt/fman/fman
The X11 connection broke: Maximum allowed requested length exceeded (code 4)
XIO: fatal IO error 22 (Das Argument ist ungültig) on X server ":51.0"
after 389 requests (389 known processed) with 0 events remaining.

sudo /opt/fman/fman
QStandardPaths: wrong ownership on runtime directory /run/user/55013, 55013 instead of 0
The X11 connection broke: Maximum allowed requested length exceeded (code 4)
XIO: fatal IO error 11 (Die Ressource ist zur Zeit nicht verfügbar) on X server ":51.0"
after 389 requests (389 known processed) with 0 events remaining.

Ubuntu runs in a virtual machine and I do have Qt installed for development.

Do you have any idea what is going on ?

thanks,
Thomas

uname -v
#143-Ubuntu SMP Mon Apr 2 16:08:24 UTC 2018

Reproduce the launch from /opt/fman/fman in the reported Ubuntu virtual machine and capture the X11 error output. Compare normal and sudo launches, including the runtime-directory warning, then determine what environment or startup condition prevents fman from opening. Done means fman starts successfully in the reported setup without the X11 connection failure.