NullReferenceException: Object reference not set to an instance of an object
UnityEngine.UI.Graphic.OnRebuildRequested () (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/Graphic.cs:399)
UnityEngine.UI.GraphicRebuildTracker.OnRebuildRequested () (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/GraphicRebuildTracker.cs:33)
UnityEngine.CanvasRenderer.RequestRefresh () (at C:/buildslave/unity/build/artifacts/generated/common/modules/CanvasRendererBindings.gen.cs:244)
I deleted a script but it still was attached as a component to an object in my hierarchy.
You have to find that script and remove it as a component.
After that it should work!
For me, I had no scripts, but I did have duplicate names for an Item Database and a Mob Database.