No groups found error after updating Unity when trying to enter play mode

I have just updated Unity from 2019.4 to 2020.2, and now when i try to enter play mode i get this incredibly unhelpful message. I have no idea how to fix this, what a group is nor what a buildscript is.

What can i do to resolve this issue?

rebuild the bundles?

Done that no change, in the end i just reverted back to 2019.4