What should i do? [Map needs lighting rebuilt warning]

I don’t know what to do to fix it
it happens when i build

That’s a normal warning to let you know that the map needed lighting to be built. This happens whenever you change any geometry or light sources. As long as you have built using the “Build All” option it will automatically build the lights for you and update the texture streaming.

ok, but the model turn all black after the building

Do you have a light source?

yes of course