till yesterday all was normal, this morning nothing work! The system (Plasma version) start normally but is impossible to start every program from the Desktop. After some trying (downgrading some components) I was able to start the terminal and to try to launch some program from the terminal and to see the effect: very very strange:
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$ freetube
Authorization required, but no authorization protocol specified
[7393:0287/084741.951014:ERROR:browser_main_loop.cc(1408)] Unable to open X display
The futex facility returned an unexpected error code
Aborted
$ palemoon
Authorization required, but no authorization protocol specified
Error: cannot open display: :0
$ octopi
Authorization required, but no authorization protocol specified
qt.qpa.xcb: could not connect to display :0
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was founf.
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, minima1, minimalegl,offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.
Aborted
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This is all I was able to obtain. Any idea? I'd like to avoid to reinstall all... its an ancrypted disk with all my work critical data.
Thank you for the help.
I discover a partial solution to the problem: deconnecting from the WI-FI all work! WTF is? :-)))
Now I'm connected with the mobile, that is connected to the standard router and all work.
Any idea about what there is to do? The hostname is defined correctly, for what I can see.
Thank you
NetworkManager (https://wiki.artixlinux.org/Main/Troubleshooting#Applications_won.27t_open_while_Wireless_connection_is_active).
Thanks' for the answer, now all work.