XIO: fatal IO error 11 (Resource temporarily unavailable) on X server ":0" after 904 requests (904 known processed) with 0 events rem
 

This error has occurred before, and went away "by itself", but now is constant. Have tried restarting X, restart Chromebook, etc. My app uses X/Motif, Opengl. It seemed to start as I added the ability to read PNG and WebP files. The latter requires pthreads, though error occurs even if not reading WebP. The initial windows display for an instant, then crashes. I do parallel development on Ubuntu 20.04 Sys76 machine, with no such problems. This X problem seems quite common, X server problem? threads?

I withdraw this problem. Apparently, some symbolic links went "stale". I removed link, then relinked. all ok