When logout/shustdown/reboot is triggered for the first time since boot, Jun 01 10:13:41 ged kwin_x11[601]: libkwinglutils: Failed to compile fragment shader: "0:13(12): error: no matching function for call to `smoothstep(int, float, float)'; candidates are:\n0:13(12): error: float smoothstep(float, float, float)\n0:13(12): error: vec2 smoothstep(float, float, vec2)\n0:13(12): error: vec3 smoothstep(float, float, vec3)\n0:13(12): error: vec4 smoothstep(float, float, vec4)\n0:13(12): error: vec2 smoothstep(vec2, vec2, vec2)\n0:13(12): error: vec3 smoothstep(vec3, vec3, vec3)\n0:13(12): error: vec4 smoothstep(vec4, vec4, vec4)\n\x00" Jun 01 10:13:41 ged kwin_x11[601]: libkwinglutils: Failed to link shader: "error: program lacks a fragment shader\n\x00" Appears in the log. I have no idea if it's in kwin, or in the graphics driver, so I'm starting here. GPU is Radeon HD6950, driver is r600g on mesa 11.2.2. OpenGl 3.1 rendering backend. Reproducible: Always Steps to Reproduce: 1. Boot, login 2. Watch journal 3. click logout
can you please paste the output of: qdbus org.kde.KWin /KWin supportInformation This should tell us which code path is used (as shaders differ depening on Version).
Created attachment 99299 [details] supportInformation output
ah it's OpenGL ES 3.
The effect in question (logout) got dropped with KWin 5.8 due to changes in the logout handling. Given that it doesn't make any sense to adjust the shader for OpenGL ES usage.