There’s something wrong with one of your GUI functions (i think it happened to me when i didnt close properly a while back)
if its not too much, you can paste your code and maybe we can find it?
Alternatively you can:
Click (or double click) on the Error, does it take you to the problematic line in the code?
Try to debug manually, comment out all your suspicious GUI functions and de comment 1 by 1?
Best thing would be to show your code, GUI.BeginGroup GUI.EndGroup() etc ’
I’ve been running into this exact error with every project since I started using Unity again a few months ago. All my projects have been the standard 2D setup (with the built-in pipeline), 2019 LTS. I’m getting it now with a prototype I started today, with no UI stuff (no UI Toolkit, no IMGUI, no UGUI) and just a fistful of standard objects as placeholders and a couple scripts.