The first thing to do when something does not work is updating your graphics card drivers.

If you have a question that is not listed here, mail me at mail@katrinlang.de, and I will list it.

My program crashes when starting up

Try decreasing the shadow map size. Look for a line saying shadow.setMapSize(2048); and set it to a lower power of two. This may result in aliasing artifacts, but at least the rest of the program will run.

I get a shader not supported error and/or shading/shadows do not work

Try decreasing the number of lights in the main shader. To do this edit the line #define MAX_LIGHTS 8 in both main-shader.vert and main-shader.frag in your sketch's data folder and set it to the number of lights you are actually using.

Object space algorithms do not work

Object space algorithms currently only work for triangle meshes. Make sure your model is a triangle mesh.