weird error(without doing anything in Unity)

Unity Engine
1

I’m using Unity 2020.2.0a11

5919536--632456--mójbłąd.PNG
5919536--632456--mójbłąd.PNG798×34 3.75 KB

2

Window → Layouts → Revert Factory Settings…

This is a very common thing when you open different projects, only some of which have certain assets or packages installed which have dedicated windows, like ProBuilder.