libGL Warning: 3D Driver Claims to Not Support 0x5b

This error is very rare and only occurs for certain combinations of graphics cards and Linux distributions. A possible solution appears to be to by-pass the non-working drivers and use software 3D rendering, by writing in terminal before starting QuantumATK:

export LIBGL_ALWAYS_INDIRECT=true

The real solution would however be to get a better graphics card and/or proper OpenGL drivers (which however is not always possible for all Linux distributions and all cards).

For more information on graphics setup and common issues refer to Graphics in QuantumATK.