Why are there thin shadow lines in mid-air extruding from my model?

Added on by Gustav Olsson.

This artefact is caused by having anti-aliasing enabled when using the "Alpha Channel" backend. To fix the problem, either switch to the "Stencil Buffer" backend (on the ShadowVolumeRenderer component) or disable anti-aliasing.

In Unity, Quality settings above Good all have some form of anti-aliasing enabled by default, so make sure that you double check all of these presets if you let the end-user choose which setting to use.