Something went wrong while Post Processing the assembly (TestRunner.dll and UI.dll)

Hi, I’m having issues building my player. I’m using multiple preview packages, and recently upgraded to 2019.3.11f1. I don’t know how recently this problem started, but I can’t find anything online for it.
Here’s the relevant part of the stack trace:
Something went wrong while Post Processing the assembly (UnityEngine.TestRunner.dll) :
The type initializer for ‘Unity.Properties.CodeGen.Utility’ threw an exception.
at Unity.Properties.CodeGen.PostProcessor.Generate (Mono.Cecil.AssemblyDefinition assembly, System.Collections.Generic.IEnumerable`1[T] defines) [0x0000e]
I get the exact same stack trace from UnityEngine.UI.dll
The code works as expected in editor. Properties version is 1.1.1-preview

Found the source of the problem, it was the packagemanagerassembly of an extremely outdated asset I downloaded (and didn’t have updated), I’m guessing the updates made it a problem. Deleting the packagemanagerassembly folder (with the import list and dll inside it) is letting me compile now.