New exception with latest Unity and DOTS components

I upgraded my project yesterday to Unity 2019.3.12f1 This morning multiple DOTS components were available for update, and since I am having another issue with Unity Physics (details https://forum.unity.com/threads/itriggereventsjob-schedule-compile-error.877681/#post-5779852) so I thought maybe the updates would resolve this. Instead I am now getting a run-time exception:

ArgumentException: System does not exist in the world
Unity.Entities.World.RemoveSystemInternal (Unity.Entities.ComponentSystemBase system) (at Library/PackageCache/com.unity.entities@0.10.0-preview.6/Unity.Entities/World.cs:425)
Unity.Entities.World.AddSystem_OnCreate_Internal (Unity.Entities.ComponentSystemBase system) (at Library/PackageCache/com.unity.entities@0.10.0-preview.6/Unity.Entities/World.cs:416)
Unity.Entities.World.GetOrCreateSystemsAndLogException (System.Type[] types) (at Library/PackageCache/com.unity.entities@0.10.0-preview.6/Unity.Entities/World.cs:614)
UnityEngine.Debug:LogException(Exception)
Unity.Debug:LogException(Exception) (at Library/PackageCache/com.unity.entities@0.10.0-preview.6/Unity.Entities/Stubs/Unity/Debug.cs:19)
Unity.Entities.World:GetOrCreateSystemsAndLogException(Type[]) (at Library/PackageCache/com.unity.entities@0.10.0-preview.6/Unity.Entities/World.cs:618)
Unity.Entities.DefaultWorldInitialization:AddSystemsToRootLevelSystemGroups(World, Type[]) (at Library/PackageCache/com.unity.entities@0.10.0-preview.6/Unity.Entities.Hybrid/Injection/DefaultWorldInitialization.cs:127)
Unity.Entities.DefaultWorldInitialization:Initialize(String, Boolean) (at Library/PackageCache/com.unity.entities@0.10.0-preview.6/Unity.Entities.Hybrid/Injection/DefaultWorldInitialization.cs:106)
Unity.Entities.AutomaticWorldBootstrap:Initialize() (at Library/PackageCache/com.unity.entities@0.10.0-preview.6/Unity.Entities.Hybrid/Injection/AutomaticWorldBootstrap.cs:15)

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I am also, within Visual Studio, getting a few dozen exceptions with a few different components that are now throwing exceptions. I BELIEVE this is a situation where the first issue, whichever that is, is causing a cascade of issues.

Any thoughts?

 

Well, I found this page/code that shows the same exception: https://github.com/Unity-Technologi...ities@0.3.0-preview.4/Unity.Entities/World.cs

However, it would be good to know why this is happening.

Anyone? Bueller? Bueller?