Crash when attempting to load existing world

Since latest update, after attempting to load a world I've spent months of time on, the world crashes. This is at the end of the crash log:

\VoxelMaps\MediumStoneIronCoreStoneCoverage.vx2'
2019-10-25 17:31:52.889 - Thread: 1 -> Exception occured: System.NullReferenceException: Object reference not set to an instance of an object.
at Sandbox.Game.Entities.Blocks.MyPistonBase.GetTopMatrixLocal()
at Sandbox.Game.Entities.Blocks.MyPistonBase.FillFixedData()
at Sandbox.Game.Entities.Blocks.MyPistonBase.CreateConstraint(MyAttachableTopBlockBase topBlock)
at Sandbox.Game.Entities.Blocks.MyPistonBase.Attach(MyAttachableTopBlockBase topBlock, Boolean updateGroup)
at Sandbox.Game.Entities.Blocks.MyMechanicalConnectionBlockBase.UpdateAttachState()
at Sandbox.Game.Entities.Blocks.MyMechanicalConnectionBlockBase.UpdateOnceBeforeFrame()
at Sandbox.Game.Entities.Blocks.MyPistonBase.UpdateOnceBeforeFrame()
at Sandbox.Game.Entities.MyEntities.UpdateOnceBeforeFrame()
at Sandbox.Game.Entities.MyEntities.UpdateBeforeSimulation()
at Sandbox.Game.World.MySector.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)
2019-10-25 17:31:52.891 - Thread: 1 -> Showing message
2019-10-25 17:31:54.104 - Thread: 1 -> Log Closed