Standalone Mode Crashes during level loading

Hi guys,

This bug is relacted with Navigation System.

First, my game open the Main Menu Level and when i click in “Start game Button” load level called “Loader”


“Loader” level have 8 sub-levels and based in last save game, loads the last

Here is the problem…

When i set Runtime generation to Static in sub-level, show this message


But, when i set Runtime generation to Dynamic, standalone game crashes during level load


Unknown exception - code 00000001 (first/second chance not available)

"Assertion failed: NavigationOctree [File:D:\BuildFarm\buildmachine_+

UE4Editor_Core!FDebug::AssertFailed() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\private\misc\outputdevice.cpp:355]
UE4Editor_Engine!FRecastTileGenerator::GatherGeometry() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\recastnavmeshgenerator.cpp:1797]
UE4Editor_Engine!FRecastTileGenerator::Setup() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\recastnavmeshgenerator.cpp:1629]
UE4Editor_Engine!FRecastNavMeshGenerator::CreateTileGenerator() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\recastnavmeshgenerator.cpp:3937]
UE4Editor_Engine!FRecastNavMeshGenerator::ProcessTileTasks() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\recastnavmeshgenerator.cpp:3961]
UE4Editor_Engine!FRecastNavMeshGenerator::TickAsyncBuild() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\recastnavmeshgenerator.cpp:3355]
UE4Editor_Engine!ANavigationData::TickAsyncBuild() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\navigationdata.cpp:490]
UE4Editor_Engine!UNavigationSystem::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\navigationsystem.cpp:763]
UE4Editor_Engine!UWorld::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\leveltick.cpp:1152]
UE4Editor_Engine!UGameEngine::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\gameengine.cpp:897]
UE4Editor!FEngineLoop::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\launchengineloop.cpp:2359]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]

Hi ,

Can you post your crash logs here so we can take a look? Additionally, does this occur in a clean, blank project with no additional content or is it limited to your project specifically?

[link text][1]

Yes, happens in a blank project too.
But one detail, this crack happens when i mark
“Auto create navigation data” to true


BUT, if i set FALSE, not crash, but nobody moves and navigation system not works for anybody

This happens after server travel to any level with navigation system.

Do you have a sample project or a set of repro steps I can follow to reproduce this on my end?


  1. create a blank project
  2. create one blank map called “Menu”
  3. create another blank map called
    “Loader” or something else
  4. create another level with basic pack
    called “Level 1”
  5. in “Level 1” create a ground if
    haven’t and put “Nav Mesh Bounds
    Volume” on ground
  6. create a simple nav agent to walk
    for any location in this ground put
    on level
  7. build all and save
  8. open “Loader” map and Add “Level 1”
    as sub level
  9. open level blueprint and call load
    stream level “Level 1” on Begin Play
  10. open “Menu” level and in begin play
    on level blueprint call
  11. Press play of play in standalone

Hi ,

I’m attempting to reproduce this on my end, however I’m running into a few complications with your steps.

On 4., What do you mean when you say “basic pack”?
On 6., Do you mean an AI that walks on the navmesh or do you mean a supported agent within the settings>navigation menus?

If I could get clarification on these I can continue attempting to reproduce this on my end. Thank you!

HI ,

On 4. means when you click in new level, show 2 options, blank or default (Basic Pack) of you select default option create a level with, ground, sky, one directional light, and player start point, this is what i mean, sorry

I uploaded on dropbox a blank project (2MB) with all steps maded
link text

Hi ,

I tested the project you sent and did not see any crash. Are there any additional steps I need to take to be able to reproduce this on my end?

Hi ,

First of all, thanks for your attention,

If you set Runtime generation to Static in Nav Mesh Config, Build and play, you will see (if not crash (my shame)) “NAV MESH NEEDS TO BE REBUILD” and AIController not walk

But I discovered something about that problem,

Static not work, just say “NAV MESH NEEDS TO BE REBUILD”

When i set dynamic and put many AIControllers starting patrolling in Begin Play Event, Editor or Standalone crashes because Nav Mesh is building, i guest

Is this right? or Is this a strange behavior?

Hi ,

Can you post your dxdiag here so I can take a look?

this is it,

link text

And diagnostics file too
link text

Hi ,

I don’t see anything there that could be linked to this error. Unfortunately I still haven’t seen the crash on my end. Do you have any other steps I can take to reproduce this on my end?

Sorry, but i haven’t no more steps.

Hi ,

I haven’t been able to reproduce this with the steps provided above. I’m going to mark this as answered for tracking purposes. If you manage to find another set of repro steps or any additional information that can help lead to reproducing this error, please comment back and I’ll be happy to take another look.