Cannot start Slicer on LInux - cannot connect to X server

this is my output

Slicer: cannot connect to X server

I am running a jupyter notebook, where slicer is invoked to show images, the very first tutorial. In my bashrc i have

export SITK_SHOW_COMMAND=${HOME}/Slicer-4.11.20210226-linux-amd64/Slicer
export PATH="$PATH:${HOME}/Slicer-4.11.20200930-linux-amd64"
#export DISPLAY=localhost:1.0

an i run jupyter notebook from MobaXterm, with the following error:

QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-fabiog'
Switch to module:  "Welcome"
The X11 connection broke: I/O error (code 1)
Slicer: Fatal IO error: client killed
XIO:  fatal IO error 0 (Success) on X server "localhost:10.0"
      after 1361 requests (1361 known processed) with 0 events remaining.
free(): invalid pointer

The question was already posted here and turned out to be a configuration error on the user’s computer: