There are exactly 288 errors, all of them are because certain code elements are inaccessible due to their protection level. I tried importing installing UI builder on an empty project, it didn’t help. Could it be because i originally tried using it on the 2021 version, and then on the 2019 version? In any case, is there a way to fix it without upgrading the project to 2021 version?
There is a minimum Unity version (inside the 2019 version) when it comes to UI Builder. It depends on which version of UI Builder you’re trying to run, you can find more info here: https://discussions.unity.com/t/775534/23
This is because the UI Builder is under heavy development, they release new things in new 2019 versions in relations of it. Which I can’t detest enough.
Also your post gives me the impression that you’re upgrade and degrade your project? Degrading unity project is not supported. Shouldn’t do that at all. Ever. Use your version control system to go back before the upgrade. If you do not, use version control system (or at least make backups).
Thanks, upgrading it to the latest 2019 version worked