Errors When Building Lighting?

Whenever I start up a new project or load an old one, everything is fine at first.
When I build the lighting, all unbuilt objects and their shadows become completely black, and I haven’t the slightest clue why.

I’m pretty sure this is the result of an error, so any fixes would be much appreciated. Cheers!

(Sorry for the noob question!)

Check if your lightmap UVs are in order.

The problem is probably in Lightmap UVs. Check that you have them (or that they are generated from normal UVs on import). Additionally, if you dont want pitch black shadows, add a skylight to your scene.

This should help you out: A new, community-hosted Unreal Engine Wiki - Announcements and Releases - Unreal Engine Forums