Created attachment 124788 [details]
Error message shown in the GUI

SUMMARY


STEPS TO REPRODUCE
1. I double click in the file browser Thunar on a pdf file
2. I try to open the file like this:

$/snap/bin/okular "~/Downloads/2017-11-29_Richard Chimera, Ben Shneiderman_An Exploratory Evaluation of Three Interfaces for Browsing Large Hierarchical Tables of Contents.pdf"
2019/12/30 16:04:26.798673 cmd_run.go:889: WARNING: cannot copy user Xauthority file: open ~/.Xauthority: permission denied
No protocol specified
qt.qpa.xcb: could not connect to display :0.0
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.

Abgebrochen
$

3. 

OBSERVED RESULT
1. Okular opens with its GUI but ti tells that it could not open the file whose name contains blancs.

2. Error messages see above. What do all the other messages mean and what has to be done to fix them. Something must be utterly wrong with this snap installed Okular!

BTW: in the GUI, Open>File does not work. This error has been reported esarlier as bug 415332.


EXPECTED RESULT


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: KDE Frameworks 5.61.0
Qt Version:             Qt 5.12.3 (kompiliert gegen 5.12.3)

ADDITIONAL INFORMATION
this happens on a snap installed version of okular under Xubuntu 18.04