Your Unity console shows something like this:
TypeLoadException: Could not load type 'MyAssembly.MyType' from assembly MyAssembly.
- Open your Unity project and go to your Assets folder and search for all DLLs (Use the windows search and type: „extension:.dll“)
- Sort the results by name and check if you have a duplicate DLL file in your results and remove duplicates. If one DLL exists inside an Editor folder, then ensure to remove the DLL which is inside that Editor folder.