Bug MissingMethodException: void

I'm trying to upgrade to 2020.2.0b8.3329. After starting, after a random amount of time, whenever I select anything, I get the following error and the inspector stays blank:

Code (Boo):

1. MissingMethodException: void UnityEditor.UIElements.EditorElement..ctor(int,UnityEditor.IPropertyView,bool)
2. UnityEditor.PropertyEditor.DrawEditors (UnityEditor.Editor[] editors) (at /Users/bokken/buildslave/unity/build/Editor/Mono/Inspector/PropertyEditor.cs:1595)
3. UnityEditor.PropertyEditor.RebuildContentsContainers () (at /Users/bokken/buildslave/unity/build/Editor/Mono/Inspector/PropertyEditor.cs:790)
4. UnityEditor.InspectorWindow.RedrawFromNative () (at /Users/bokken/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:147)
5.  

The editor does not recover from this and I have to restart.

P.S: I'll submit a bug report and post the case # here.

 

Case 1287326.

 

If anybody has this issue and knows how to (even just temporarily) fix it, I'd be interested to know how

 

Sadly there are too many Editor UI related errors for me to stay on 2020.2

 

Do you happen to have the UI Toolkit package in your project?
If yes, it is incompatible with Unity versions after 2020.2.0b2.

You have to either remove it or stick to 2020.2.0b2 (I suggest b1 as b2 has an horrible bug with particle systems.)

 

Thanks @b4gn0! That is great to know. I do have the UI Toolkit 1.0.0-preview.9 installed and will try 2020.2.0b1.

Edit: Sadly, with 2020.2.0b1, the editor repeatedly (forever) asks me to use the default layout, while failing with this error:

Code (CSharp):

1. [LAYOUT] About to load Library/CurrentLayout-default.dwlt, keepMainWindow=False
2. Failed to load window layout: System.NullReferenceException: Object reference not set to an instance of an object
3.   at UnityEditor.ContainerWindow.GetWindowID () [0x0006a] in /Users/bokken/buildslave/unity/build/Editor/Mono/ContainerWindow.cs:339
4.   at UnityEditor.ContainerWindow.get_windowID () [0x00010] in /Users/bokken/buildslave/unity/build/Editor/Mono/ContainerWindow.cs:81
5.   at UnityEditor.ContainerWindow.SaveGeometry () [0x00001] in /Users/bokken/buildslave/unity/build/Editor/Mono/ContainerWindow.cs:363
6.   at UnityEditor.ContainerWindow.Save () [0x0000d] in /Users/bokken/buildslave/unity/build/Editor/Mono/ContainerWindow.cs:378
7.   at UnityEditor.ContainerWindow.Close () [0x00001] in /Users/bokken/buildslave/unity/build/Editor/Mono/ContainerWindow.cs:310
8.   at UnityEditor.WindowLayout.LoadWindowLayout (System.String path, System.Boolean newProjectLayoutWasCreated, System.Boolean setLastLoadedLayoutName, System.Boolean keepMainWindow) [0x000db] in /Users/bokken/buildslave/unity/build/Editor/Mono/GUI/WindowLayout.cs:1020
9. #0 GetStacktrace(int)
10. #1 DebugStringToFile(DebugStringToFileData const&)
11. #2 DebugLogHandler::Internal_Log(LogType, LogOption, core::basic_string<char, core::StringStorageDefault<char> >, Object*)
12. #3 DebugLogHandler_CUSTOM_Internal_Log(LogType, LogOption, ScriptingBackendNativeStringPtrOpaque*, ScriptingBackendNativeObjectPtrOpaque*)
13. #4  (Mono JIT Code) (wrapper managed-to-native) UnityEngine.DebugLogHandler:Internal_Log (UnityEngine.LogType,UnityEngine.LogOption,string,UnityEngine.Object)
14. #5  (Mono JIT Code) [WindowLayout.cs:983] UnityEditor.WindowLayout:LoadWindowLayout (string,bool)
15. #6  (Mono JIT Code) [WindowLayout.cs:338] UnityEditor.WindowLayout:LoadProjectLayout (bool)

Edit 2: First moving to e.g. b8, then back to b1 works to overcome the editor loading issue.