Why does Unity crash on DX12?

Hello! I use Unity 2018.2 and It runs with DX11. I hoped Unity runs with DX12. So I tried Unity running with DX12 many times. But, It always crashed. I couldn't search how to resolve the problem. Could you teach me why Unity crash and how to resolve? I am sorry for my poor English. Thank you!

p.s. My computer's specification CPU : RYZEN5 2600 GPU : RX580 RAM : DDR4 2400MHz 16GB Unity 2018.2.15