EDIT: here is a pastebin of a log: https://pastebin.com/27N1VkNH

This one isn't an issue with the mod from what I can tell - typically mod issues will trigger a message about the offending class. You'll likely want to ask about that one on the Keen Forum/Discord

Ok - thanks for the reply. Strange though. Only happens when I load this mod :( Pity coz I've seen it on many youtube channels and looks cool

Exception occured: System.ArgumentNullException: Value cannot be null.
Parameter name: key
at System.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
at System.Collections.Generic.Dictionary`2.FindEntry(TKey key)
at ModularEncountersSpawner.Spawners.SpaceCargoShipSpawner.GetSpaceCargoShips(Vector3D playerCoords)
at ModularEncountersSpawner.Spawners.SpaceCargoShipSpawner.AttemptSpawn(Vector3D startCoords)
at ModularEncountersSpawner.MES_SessionCore.ProcessPlayerWatchList()
at ModularEncountersSpawner.MES_SessionCore.UpdateBeforeSimulation()
at Sandbox.Game.World.MySession.UpdateComponents()
at Sandbox.Game.World.MySession.Update(MyTimeSpan updateTime)
at Sandbox.MySandboxGame.Update()
at Sandbox.Engine.Platform.Game.UpdateInternal()
at Sandbox.Engine.Platform.Game.RunSingleFrame()
at Sandbox.Engine.Platform.FixedLoop.<>c__DisplayClass11_0.<Run>b__0()
at Sandbox.Engine.Platform.GenericLoop.Run(VoidAction tickCallback)
at Sandbox.Engine.Platform.Game.RunLoop()
at Sandbox.MySandboxGame.Run(Boolean customRenderLoop, Action disposeSplashScreen)
at SpaceEngineers.MyProgram.Main(String[] args)

Been fighting with this crash all night...

I am having this EXACT same issue since the update was made last night. I use the Modular Encounters mod as the core of my server scenario but am unable to run it currently.