NullRef at HierarchicalGraph.RecalculateIfNecessary()

1

After unloading current level and loading a new one, we call AstarPath.Scan(), but sometimes we get a error:

NullReferenceException: Object reference not set to an instance of an object.
  at Pathfinding.HierarchicalGraph.RecalculateIfNecessary () [0x00000] in <00000000000000000000000000000000>:0 
  at Pathfinding.WorkItemProcessor.ProcessWorkItems (System.Boolean force) [0x00000] in <00000000000000000000000000000000>:0 
  at AstarPath.PerformBlockingActions (System.Boolean force) [0x00000] in <00000000000000000000000000000000>:0 
  at AstarPath.FlushThreadSafeCallbacks () [0x00000] in <00000000000000000000000000000000>:0 
  at AstarPath+<ScanAsync>d__141.MoveNext () [0x00000] in <00000000000000000000000000000000>:0 
  at AstarPath.Scan (Pathfinding.NavGraph[] graphsToScan) [0x00000] in <00000000000000000000000000000000>:0 
  at Island.EndIslandInitialization () [0x00000] in <00000000000000000000000000000000>:0 
  at UnityEngine.AI.NavMesh+OnNavMeshPreUpdate.Invoke () [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.Timer.Update (System.Single currentTime) [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.LazyTimer.Update () [0x00000] in <00000000000000000000000000000000>:0 

InvalidOperationException: Another async scan is already running
  at AstarPath+<ScanAsync>d__141.MoveNext () [0x00000] in <00000000000000000000000000000000>:0 
  at AstarPath.Scan (Pathfinding.NavGraph[] graphsToScan) [0x00000] in <00000000000000000000000000000000>:0 
  at Island.EndIslandInitialization () [0x00000] in <00000000000000000000000000000000>:0 
  at UnityEngine.AI.NavMesh+OnNavMeshPreUpdate.Invoke () [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.Timer.Update (System.Single currentTime) [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.LazyTimer.Update () [0x00000] in <00000000000000000000000000000000>:0 

InvalidOperationException: Another async scan is already running
  at AstarPath+<ScanAsync>d__141.MoveNext () [0x00000] in <00000000000000000000000000000000>:0 
  at AstarPath.Scan (Pathfinding.NavGraph[] graphsToScan) [0x00000] in <00000000000000000000000000000000>:0 
  at Island.EndIslandInitialization () [0x00000] in <00000000000000000000000000000000>:0 
  at UnityEngine.AI.NavMesh+OnNavMeshPreUpdate.Invoke () [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.Timer.Update (System.Single currentTime) [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.LazyTimer.Update () [0x00000] in <00000000000000000000000000000000>:0 

InvalidOperationException: Another async scan is already running
  at AstarPath+<ScanAsync>d__141.MoveNext () [0x00000] in <00000000000000000000000000000000>:0 
  at AstarPath.Scan (Pathfinding.NavGraph[] graphsToScan) [0x00000] in <00000000000000000000000000000000>:0 
  at Island.EndIslandInitialization () [0x00000] in <00000000000000000000000000000000>:0 
  at UnityEngine.AI.NavMesh+OnNavMeshPreUpdate.Invoke () [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.Timer.Update (System.Single currentTime) [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.LazyTimer.Update () [0x00000] in <00000000000000000000000000000000>:0 

InvalidOperationException: Another async scan is already running
  at AstarPath+<ScanAsync>d__141.MoveNext () [0x00000] in <00000000000000000000000000000000>:0 
  at AstarPath.Scan (Pathfinding.NavGraph[] graphsToScan) [0x00000] in <00000000000000000000000000000000>:0 
  at Island.EndIslandInitialization () [0x00000] in <00000000000000000000000000000000>:0 
  at UnityEngine.AI.NavMesh+OnNavMeshPreUpdate.Invoke () [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.Timer.Update (System.Single currentTime) [0x00000] in <00000000000000000000000000000000>:0 
  at LazyBearTechnology.LazyTimer.Update () [0x00000] in <00000000000000000000000000000000>:0 

..... (and so on) ....

As it shows only sometimes and on slow platforms, that seems to be something with async processes.

2

Hi

That’s unfortunate. Which version are you using? Would it be possible for you to try out the beta (A* Pathfinding Project). Also, would it be possible for you to do a debug build so that line numbers show up?