How to make trees impassable?

I did try putting mesh collider in it too. It just won’t work. Can someone help me? I just walk through every trees.

Kind of sucks to do, but put box colliders around each one. Mesh colliders are only really useful for flat ground surfaces and boundaries, because on complex models they don’t work too well, and that would make your game perform badly.

Tip: once you’ve created one box collider for one tree, just keep duplicating it and move it to the next one, so you don’t have to keep sizing them.