Upgrading from 2019.3.7 makes infinite import loop

Hi. I found that upgrading 2019.3.7 to Unity 2020.1.0b4 makes infinite import loop. After a while editor showup, but I can't access any FBX and prefab asset. It shows rotating "loading indicator" on its icon and I can't click it on Project view.

Console log shows infinite import loop found. But even it contains not only json file on Mathematics package. Upgrading to 2020.1.0b1~2 doesn't make this issue.

I found that automatically updated ShaderGraph and URP packages make problem. First time it automatically updated from 7.3.1 to 8.0.1 and it doesn't work with 2020.1 beta.

After opened Unity editor window, I manually update it to 9.0.0-preview and issue is gone.