OK, I am new, but I can’t find a tutorial that explains this and after one day of trying I am about to give it all up in utter frustration:
I imported a terrain, set it to Terrain collider (component/Physics/Terrain collider) then I set the First Person Controller to Mesh Collider, yet when I press play the FPController falls through the floor. I have been working on this all day now trying different terrains, starting from scratch and using different colliders. What is wrong please?
tThe terrain collider is only for Unity Terrain objects. That is a special kind of mesh that Unity does special LOD adjustments to at runtime. You create it through GameObject → Create Other → Terrain, and edit it inside the Unity editor with special tools that show up inside the inspector.
You are just using a mesh object as your terrain so you need to add a mesh collider to it instead.
You also do not need a mesh collider added to your character object. The CharaterController is a type of collider itself. You may want to add a capsule collider and a kinematic rigidbody to your character to properly detect collisions with other objects.
Thank you very much, that was extremely helpful 
