An exception occured during VehicleAI simulation step.
Asset: 463864579.Volvo FH '14 (Wood)_Data
VehicleID: 12294
Type: CargoTruckAI
Severity: High

System.NullReferenceException: Object reference not set to an instance of an object
at ColossalFramework.Math.Segment3.DistanceSqr (Vector3 p, System.Single+ u) [0x00000] in <filename unknown>:0
at TrafficManager.Custom.AI.CustomCarAI.CustomCheckOtherVehicle (UInt16 vehicleId, .Vehicle+ vehicleData, .Frame+ frameData, System.Single+ maxSpeed, System.Boolean+ blocked, UnityEngine.Vector3+ collisionPush, Single maxBraking, UInt16 otherID, .Vehicle+ otherData, Vector3 min, Vector3 max, Int32 lodPhysics) [0x00000] in <filename unknown>:0
at CarAI.CheckOtherVehicles (UInt16 vehicleID, .Vehicle+ vehicleData, .Frame+ frameData, System.Single+ maxSpeed, System.Boolean+ blocked, UnityEngine.Vector3+ collisionPush, Single maxDistance, Single maxBraking, Int32 lodPhysics) [0x00000] in <filename unknown>:0
at CarAI.SimulationStep (UInt16 vehicleID, .Vehicle+ vehicleData, .Frame+ frameData, UInt16 leaderID, .Vehicle+ leaderData, Int32 lodPhysics) [0x00000] in <filename unknown>:0
at VehicleAI.SimulationStep (UInt16 vehicleID, .Vehicle+ vehicleData, UInt16 leaderID, .Vehicle+ leaderData, Int32 lodPhysics) [0x00000] in <filename unknown>:0
at TrafficManager.Custom.AI.CustomCarAI.CustomSimulationStep (UInt16 vehicleId, .Vehicle+ vehicleData, Vector3 physicsLodRefPos) [0x00000] in <filename unknown>:0
at TrafficManager.Custom.AI.CustomCargoTruckAI.CustomSimulationStep (UInt16 vehicleId, .Vehicle+ vehicleData, Vector3 physicsLodRefPos) [0x00000] in <filename unknown>:0
at HealkitMod.Patches.VehicleManagerPatch.SimulationStep (.VehicleAI _this, UInt16 vehicleID, .Vehicle+ data, Vector3 physicsLodRefPos) [0x00000] in <filename unknown>:0

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suddenly this error pops up with everytime different name of vehicle in the name!
Looks like TMPE is losing it.

Am I right?

Hard to say for sure, as traffic manager just copies much of the vanilla game code.

@WONHO OPPA
Loading Screen Mod "Safe Mode" options can sometimes recover from the error - see
https://github.com/CitiesSkylinesMods/TMPE/wiki/Object-reference-not-set-to-an-instance-of-an-object

both! thanks for reaction.
error is going again also temperairly removed TMPE.
because pc runs smoother without it!

System.NullReferenceException: Object reference not set to an instance of an object
at ZoneBlock.CalculateBlock3 (UInt16 blockID) [0x00000] in <filename unknown>:0
at ZoneManager.SimulationStepImpl (Int32 subStep) [0x00000] in <filename unknown>:0
at SimulationManagerBase`2[Manager,Properties].SimulationStep (Int32 subStep) [0x00000] in <filename unknown>:0
at ZoneManager.ISimulationManager.SimulationStep (Int32 subStep) [0x00000] in <filename unknown>:0
at SimulationManager.SimulationStep () [0x00000] in <filename unknown>:0
at SimulationManager.SimulationThread () [0x00000] in <filename unknown>:0

It suddenly apeared, and there is no way no close the error window

System.NullReferenceException: Object reference not set to an instance of an object
at BuildingAI.CheckUnlocking () <0x0002f>
at (wrapper dynamic-method) BuildingManager.SimulationStepImpl_Patch0 (object,int) <0x00d91>
at SimulationManagerBase`2.SimulationStep (int) <0x0004c>
at BuildingManager.ISimulationManager.SimulationStep (int) <0x00024>
at SimulationManager.SimulationStep () <0x00693>
at SimulationManager.SimulationThread () <0x0018a>

For the Object Reference Errors this is a good reference point:
https://github.com/CitiesSkylinesMods/TMPE/wiki/Object-reference-not-set-to-an-instance-of-an-object

An exception occured during VehicleAI simulation step.
Asset: Sedan
VehicleID: 1618
Type: PassengerCarAI
Severity: High

System.NullReferenceException: Object reference not set to an instance of an object
at TrafficManager.Manager.Impl.ParkingRestrictionsManager.IsParkingAllowed (UInt16 segmentId, Direction finalDir) [0x00000] in <filename unknown>:0
at TrafficManager.Manager.Impl.AdvancedParkingManager+<>c__DisplayClass26_0.<FindParkingSpaceAtRoadSide>g__LoopHandler

Hi guys would love some help on this error, i really dont know how to fix it. When i launched my city, this error message kept popping up. I had to force quit the game.

An exception occured during CitizenAI simulation step.
Asset: Educated Male 2
CitizenID: 576186
Type: ResidentAI
Severity: High

System.NullReferenceException: Object reference not set to an instance of an object
at ResidentAI.UpdateWellbeing (UInt32 citizenID, .Citizen+ data) [0x00000] in <filename unknown>:0
at ResidentAI.SimulationStep (UInt32 citizenID, .Citizen+ data) [0x00000] in <filename unknown>:0
at HealkitMod.Patches.CitizenManagerPatch.SimulationStep (.CitizenAI _this, UInt32 citizenID, .Citizen+ data) [0x00000] in <filename unknown>:0

@soso.lakers - To be honest it always is more helpful to have the entire log than just one tiny section of it at any time. My analogy is always it is like trying to tell someone the plot of a book based on 1 paragraph in the middle.

Do you get the error even after exiting to desktop and reloading?

System.NullReferenceException: Object reference not set to an instance of an object
at TrainTrackBaseAI.UpdateLanes (uint16,NetSegment+,bool) <0x005d0>
at NetSegment.UpdateLanes (uint16,bool) <0x00092>
at NetNode.CheckHeightOffset (uint16) <0x0045a>
at NetNode.TerrainUpdated (uint16,single,single,single,single) <0x00aee>
at NetManager.TerrainUpdated (TerrainArea,TerrainArea,TerrainArea) <0x00534>
at TerrainManager.Managers_TerrainUpdated (TerrainArea,TerrainArea,TerrainArea) <0x0005e>
at TerrainModify.UpdateAreaImplementation () <0x018f1>
at TerrainModify.UpdateArea (int,int,int,int,bool,bool,bool) <0x0066b>
at TerrainManager.UpdateData (SimulationManager/UpdateMode) <0x000ef>
at (wrapper dynamic-method) SimulationManager.Managers_UpdateData_Patch2 (SimulationManager/UpdateMode,single,single) <0x00105>
at LoadingManager/<LoadSimulationData>c__IteratorB.MoveNext () <0x00bdf>
at AsyncTask.Execute () <0x000a8>

System.NullReferenceException: Object reference not set to an instance of an object
at WaterSimulation.ReleaseWaterWave (UInt16 wave) [0x00000] in <filename unknown>:0
at DisasterManager.ReleaseDisaster (UInt16 disasterIndex) [0x00000] in <filename unknown>:0
at DisasterManager.SimulationStepImpl (Int32 subStep) [0x00000] in <filename unknown>:0
at SimulationManagerBase`2[Manager,Properties].SimulationStep (Int32 subStep) [0x00000] in <filename unknown>:0
at DisasterManager.ISimulationManager.SimulationStep (Int32 subStep) [0x00000] in <filename unknown>:0
at SimulationManager.SimulationStep () [0x00000] in <filename unknown>:0
at SimulationManager.SimulationThread () [0x00000] in <filename unknown>:0

System.NullReferenceException: Object reference not set to an instance of an object
at BuildingAI.CheckUnlocking () <0x0002f>
at (wrapper dynamic-method) BuildingManager.SimulationStepImpl_Patch0 (object,int) <0x00d91>
at SimulationManagerBase`2.SimulationStep (int) <0x0004c>
at BuildingManager.ISimulationManager.SimulationStep (int) <0x00024>
at SimulationManager.SimulationStep () <0x00693>
at SimulationManager.SimulationThread () <0x0018a>

No idea what is causeing it