4.21.0 Crash in RecastNavMesh on Editor Startup

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1

Not sure what detail i can give but my 4.20 project with a navmesh crashes on startup of the editor with 4.21.

UE4Editor-NavigationSystem.dll!UClass::GetDefaultObject<UNavigationSystemV1 const >() Line 2479
    	at d:\build\++ue4\sync\engine\source\runtime\coreuobject\\uobject\class.h(2479)
    UE4Editor-NavigationSystem.dll!FNavigationSystem::ShouldLoadNavigationOnClient(ANavigationData & NavData) Line 133
    	at d:\build\++ue4\sync\engine\source\runtime\navigationsystem\private\navigationsystem.cpp(133)
    UE4Editor-NavigationSystem.dll!ANavigationData::PostInitProperties() Line 170
    	at d:\build\++ue4\sync\engine\source\runtime\navigationsystem\private\navigationdata.cpp(170)
    UE4Editor-NavigationSystem.dll!ARecastNavMesh::PostInitProperties() Line 404
    	at d:\build\++ue4\sync\engine\source\runtime\navigationsystem\private\navmesh\recastnavmesh.cpp(404)
    UE4Editor-CoreUObject.dll!FObjectInitializer::PostConstructInit() Line 2842
    	at d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp(2842)
    UE4Editor-CoreUObject.dll!FObjectInitializer::~FObjectInitializer() Line 2699
    	at d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp(2699)
    UE4Editor-CoreUObject.dll!StaticConstructObject_Internal(UClass * InClass, UObject * InOuter, FName InName, EObjectFlags InFlags, EInternalObjectFlags InternalSetFlags, UObject * InTemplate, bool bCopyTransientsFromClassDefaults, FObjectInstancingGraph * InInstanceGraph, bool bAssumeTemplateIsArchetype) Line 3160
    	at d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp(3160)
    UE4Editor-CoreUObject.dll!FLinkerLoad::CreateExport(int Index) Line 4173
    	at d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\linkerload.cpp(4173)
    UE4Editor-CoreUObject.dll!FLinkerLoad::CreateExportAndPreload(int ExportIndex, bool bForcePreload) Line 2960
    	at d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\linkerload.cpp(2960)
    UE4Editor-CoreUObject.dll!FLinkerLoad::LoadAllObjects(bool bForcePreload) Line 3116
    	at d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\linkerload.cpp(3116)
    UE4Editor-CoreUObject.dll!LoadPackageInternal(UPackage * InOuter, const wchar_t * InLongPackageNameOrFilename, unsigned int LoadFlags, FLinkerLoad * ImportLinker, FArchive * InReaderOverride) Line 1366
    	at d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp(1366)
    UE4Editor-CoreUObject.dll!LoadPackage(UPackage * InOuter, const wchar_t * InLongPackageName, unsigned int LoadFlags, FArchive * InReaderOverride) Line 1473
    	at d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp(1473)
    UE4Editor-UnrealEd.dll!UEditorEngine::Map_Load(const wchar_t * Str, FOutputDevice & Ar) Line 2550
    	at d:\build\++ue4\sync\engine\source\editor\unrealed\private\editorserver.cpp(2550)
    UE4Editor-UnrealEd.dll!UEditorEngine::HandleMapCommand(const wchar_t * Str, FOutputDevice & Ar, UWorld * InWorld) Line 6023
    	at d:\build\++ue4\sync\engine\source\editor\unrealed\private\editorserver.cpp(6023)
    UE4Editor-UnrealEd.dll!UEditorEngine::Exec(UWorld * InWorld, const wchar_t * Stream, FOutputDevice & Ar) Line 5500
    	at d:\build\++ue4\sync\engine\source\editor\unrealed\private\editorserver.cpp(5500)
    UE4Editor-UnrealEd.dll!UUnrealEdEngine::Exec(UWorld * InWorld, const wchar_t * Stream, FOutputDevice & Ar) Line 691
    	at d:\build\++ue4\sync\engine\source\editor\unrealed\private\unrealedsrv.cpp(691)
    UE4Editor-UnrealEd.dll!FEditorFileUtils::LoadMap(const FString & InFilename, bool LoadAsTemplate, const bool bShowProgress) Line 2396
    	at d:\build\++ue4\sync\engine\source\editor\unrealed\private\filehelpers.cpp(2396)
    UE4Editor-UnrealEd.dll!FEditorFileUtils::LoadDefaultMapAtStartup() Line 3774
    	at d:\build\++ue4\sync\engine\source\editor\unrealed\private\filehelpers.cpp(3774)
    UE4Editor-UnrealEd.dll!FUnrealEdMisc::OnInit() Line 348
    	at d:\build\++ue4\sync\engine\source\editor\unrealed\private\unrealedmisc.cpp(348)
    UE4Editor-UnrealEd.dll!EditorInit(IEngineLoop & EngineLoop) Line 97
    	at d:\build\++ue4\sync\engine\source\editor\unrealed\private\unrealedglobals.cpp(97)
    UE4Editor-Win64-DebugGame.exe!GuardedMain(const wchar_t * CmdLine, HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, int nCmdShow) Line 158
    	at d:\build\++ue4\sync\engine\source\runtime\launch\private\launch.cpp(158)
    UE4Editor-Win64-DebugGame.exe!WinMain(HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, char * __formal, int nCmdShow) Line 262
    	at d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp(262)
2

I’m experiencing the same crash as well across multiple projects while converting them to 4.21. All projects load till 93% and then they crash. I’ve tried renaming the navigation class address as suggested in the debug log shown below, but to no avail.

[2018.11.10-07.49.38:526][ 0]LogNavigation: Error: [/Script/Engine.RecastNavMesh] found in the DefaultEngine.ini file. This class has been moved. Please rename that section to [/Script/NavigationSystem.RecastNavMesh]

3

Hello,

We’ve recently made a switch to a new bug reporting method using a more structured form. Please visit the link below for more details and report the issue using the new Bug Submission Form. Feel free to continue to use this thread for community discussion around the issue.

https://epicsupport.force.com/unrealengine/s/

Thanks

4

I am having the same issue, just updated from 4.20 to 4.21, Editor crashes on opening any level that uses the NavigationSystem.

5

Hi , were you able to find any fix for this issue?

6

Same here. Tried adding nav mesh and basic AI + nav mesh related logic before converting to 4.21, but was unable to reproduce it at least when upgrading from 4.19 and 4.20.

I’ll try out your suggestion with one of my smaller projects and see if it works.

7

I am trying to reproduce this in a bare bones project and can’t if any of you could that would help epic.

By removing all things Navi, upgrading, then readding, I think you can get around it.

8

We’ve been running into this crash as well. When upgrading our project from 4.20 to 4.21 and trying to load any level with a navmesh in it, the editor would crash. Simply trying to place a navmesh volume in a level would also cause the crash. Packaging would fail.

It turns out, the issue was due to a project setting in the DefaultEngine.ini. Apparently, when upgrading a project from 4.19 to 4.20 you had to update the NavigationDataClassName in the DefaultEngine.ini to “/Script/NavigationSystem.RecastNavMesh”. That very same line now causes a crash in 4.21. So, simply removing that line from the ini fixed the issue for us.

I figured this out when reading about a navmesh error that occurred in 4.20 in this thread: UE 4.20.1 Navigation System BUG? - AI - Unreal Engine Forums

9

You are a lifesaver, HappyDay. Most of my projects were stuck in 4.20 due to this issue. And now finally I’m able to upgrade them to 4.21. Thanks a lot :slight_smile: