Crash due to EventController duplicate key exception

We have seen this exception several times a month. We have not been able to empirically prove the cause, but anecdotally, we think it is caused by welding a blueprint with Event Controllers. It does not seem to be reproducible, as rebuilding the BP does not cause the Exception.

I first started seeing these exceptions after the Core Systems Update (Nov 2025) on a different server, which makes me suspect it is not directly related to a mod or plugin.

It seems that when a BP is welded, the IDs in m_selectedBlocks are not being updated correctly. Either it is a conflict between old and updated IDs or duplicate IDs are being inserted.

This then leads to the Exception when the duplicate is added to the m_selectedBlocks Dictionary.

00:51:42.6111 [FATAL] Initializer: System.ArgumentException: An item with the same key has already been added.

at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)

at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)

at SpaceEngineers.Game.Entities.Blocks.MyEventControllerBlock.ProcessSelectedBlocks()

at SpaceEngineers.Game.Entities.Blocks.MyEventControllerBlock.UpdateAfterSimulation10()

at Patched_Sandbox.Game.Entities.MyParallelEntityUpdateOrchestratorUpdateAfterSimulation10_0(Object )

at Sandbox.Game.Entities.MyParallelEntityUpdateOrchestrator.DispatchAfterSimulation()

at Sandbox.Game.Entities.MyEntities.UpdateAfterSimulation()

at Sandbox.Game.World.MySector.UpdateAfterSimulation()

at Patched_Sandbox.Game.World.MySessionUpdateComponents_0(Object )

at Patched_Sandbox.Game.World.MySessionUpdate_0(Object , MyTimeSpan )

at Sandbox.MySandboxGame.Update()

at Patched_Sandbox.Engine.Platform.GameUpdateInternal_0(Object )

at Patched_Sandbox.Engine.Platform.GameRunSingleFrame_0(Object )

at Patched_Sandbox.Engine.Platform.FixedLoop+<>c__DisplayClass11_0<Run>b__0_0(Object )

at Sandbox.Engine.Platform.GenericLoop.Run(VoidAction tickCallback)

at Sandbox.Engine.Platform.Game.RunLoop()

at Sandbox.MySandboxGame.Run(Boolean customRenderLoop, Action disposeSplashScreen)

at Torch.VRageGame.DoStart() in C:\ProgramData\Jenkins\.jenkins\workspace\Torch_master\Torch\VRageGame.cs:line 319

at Torch.VRageGame.Run() in C:\ProgramData\Jenkins\.jenkins\workspace\Torch_master\Torch\VRageGame.cs:line 126

at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)

at System.Threading.ThreadHelper.ThreadStart()

System.ArgumentException: An item with the same key has already been added.

at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)

at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)

at SpaceEngineers.Game.Entities.Blocks.MyEventControllerBlock.ProcessSelectedBlocks()

at SpaceEngineers.Game.Entities.Blocks.MyEventControllerBlock.UpdateAfterSimulation10()

at Patched_Sandbox.Game.Entities.MyParallelEntityUpdateOrchestratorUpdateAfterSimulation10_0(Object )

at Sandbox.Game.Entities.MyParallelEntityUpdateOrchestrator.DispatchAfterSimulation()

at Sandbox.Game.Entities.MyEntities.UpdateAfterSimulation()

at Sandbox.Game.World.MySector.UpdateAfterSimulation()

at Patched_Sandbox.Game.World.MySessionUpdateComponents_0(Object )

at Patched_Sandbox.Game.World.MySessionUpdate_0(Object , MyTimeSpan )

at Sandbox.MySandboxGame.Update()

at Patched_Sandbox.Engine.Platform.GameUpdateInternal_0(Object )

at Patched_Sandbox.Engine.Platform.GameRunSingleFrame_0(Object )

at Patched_Sandbox.Engine.Platform.FixedLoop+<>c__DisplayClass11_0<Run>b__0_0(Object )

at Sandbox.Engine.Platform.GenericLoop.Run(VoidAction tickCallback)

at Sandbox.Engine.Platform.Game.RunLoop()

at Sandbox.MySandboxGame.Run(Boolean customRenderLoop, Action disposeSplashScreen)

at Torch.VRageGame.DoStart() in C:\ProgramData\Jenkins\.jenkins\workspace\Torch_master\Torch\VRageGame.cs:line 319

at Torch.VRageGame.Run() in C:\ProgramData\Jenkins\.jenkins\workspace\Torch_master\Torch\VRageGame.cs:line 126

at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)

at System.Threading.ThreadHelper.ThreadStart()