Can you update your graphics card driver?

• Upgrade your graphics drivers to use hardware acceleration and WebGL

GLXtest is a tiny glxinfo-like program. It fails because glXChooseVisual(dpy, DefaultScreen(dpy), attribs) returns NULL. That is all what I know.

My XF86 Intel video driver is up to date (2.99.906)

Does running glxinfo in a terminal window give any clues if there is something wrong?

Do you have multiple adapters installed?

I have one adapter. glxinfo says:

Error: couldn't find RGB GLX visual or fbconfig
Error: couldn't find RGB GLX visual or fbconfig

1 GLX Visuals
    visual  x   bf lv rg d st  colorbuffer  sr ax dp st accumbuffer  ms  cav
  id dep cl sp  sz l  ci b ro  r  g  b  a F gb bf th cl  r  g  b  a ns b eat
----------------------------------------------------------------------------
0x049 32 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None

If I interpret this correctly, the only available visual is 32-bit RGBA.