Resolved Constant error with "UnityEditor.Experimental.AssetImporters.ScriptedImporter"

I'm getting this error:

Code (CSharp):

1. TypeLoadException: Could not resolve type with token 01000051 from typeref (expected class 'UnityEditor.Experimental.AssetImporters.ScriptedImporter' in assembly 'UnityEditor, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null') assembly:UnityEditor, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null type:UnityEditor.Experimental.AssetImporters.ScriptedImporter member:(null)
2. UnityEditor.EditorApplication.Internal_CallUpdateFunctions () (at <462b82a54ea94e5da1dfbbc027ef8bd0>:0)

A million times and I don't know why, considering this seems to be out of experimental with unity 2021 I'm not sure this is supposed to exist in this form.

The project is upgrading from unity 2019.4, and seems to also break the package manager.

I've also tried removing all assets using "AssetImporter" but the error continues.

It does not appear in safe mode, and does not trigger safe mode when loading unity.


I've done a full reimport this does not fix it.

I've tried "Reset Packages to Defaults" it does not fix it.

This is in Unity 2021.2.0b10.3401

Please help!

 

turns out the issue was the older version of the substance source asset, updating finally fixed this.

Issue was in a dll so i couldn't see where it was coming from