I got done making a short little project in Unreal 5.6.1 and I went to go package my game for windows and it kept giving me an Error saying “Unknown Cook Failure” which is also an issue I only started having when I realised I had the wrong level set as the default one so I switched it to the one I wanted. In the crash it mentions something about a GravityGroupIndex not being less than 8, but I don’t have much experience with Unreal Engine and it’s driving me crazy trying to figure out what I’m supposed to do with that info, so I’m hoping someone can explain how to ensure that stays at 7 or lower. If I didn’t give enough info for help then let me know, I’m still very new to all of this.
(Here’s where the Errors started until the crash)
UATHelper: Packaging (Windows): LogInit: Display: LogOutputDevice: Error: begin: stack for UAT
vexe
November 11, 2025, 7:11pm
2
Getting this error as well. Not sure what to do about it. Anyone has ideas?
[2025.11.10-15.23.09:159][253]PackagingResults: Error: begin: stack for UAT
[2025.11.10-15.23.09:159][253]PackagingResults: Error: === Handled ensure: ===
[2025.11.10-15.23.09:160][253]PackagingResults: Error: Ensure condition failed: GravityGroupIndex < 8 [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Experimental\Chaos\Public\Chaos\RigidParticleControlFlags.h] [Line: 42]
[2025.11.10-15.23.09:160][253]PackagingResults: Error: Stack:
[2025.11.10-15.23.09:160][253]PackagingResults: Error: [Callstack] 0x00007ffb829effc5 UnrealEditor-PhysicsCore.dll!Chaos::TPBDRigidParticle<double,3>::SetGravityGroupIndex() [D:\build\++UE5\Sync\Engine\Source\Runtime\Experimental\Chaos\Public\Chaos\ParticleHandle.h:3410]
[2025.11.10-15.23.09:160][253]PackagingResults: Error: [Callstack] 0x00007ffb829f0054 UnrealEditor-PhysicsCore.dll!FChaosEngineInterface::SetGravityGroupIndex_AssumesLocked() [D:\build\++UE5\Sync\Engine\Source\Runtime\PhysicsCore\Private\ChaosEngineInterface.cpp:1200]
[2025.11.10-15.23.09:160][253]PackagingResults: Error: [Callstack] 0x00007ffb8b319047 UnrealEditor-Engine.dll!TInitBodiesHelperBase<TSizedInlineAllocator<1,32,TSizedDefaultAllocator<32> > >::CreateActor_AssumesLocked() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\PhysicsEngine\BodyInstance.cpp:1320]
[2025.11.10-15.23.09:160][253]PackagingResults: Error: [Callstack] 0x00007ffb8b31f2a3 UnrealEditor-Engine.dll!TInitBodiesHelperBase<TSizedInlineAllocator<1,32,TSizedDefaultAllocator<32> > >::CreateShapesAndActors() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\PhysicsEngine\BodyInstance.cpp:1541]
[2025.11.10-15.23.09:160][253]PackagingResults: Error: [Callstack] 0x00007ffb8b341f7e UnrealEditor-Engine.dll!TInitBodiesHelperBase<TSizedInlineAllocator<1,32,TSizedDefaultAllocator<32> > >::InitBodies() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\PhysicsEngine\BodyInstance.cpp:1579]
[2025.11.10-15.23.09:160][253]PackagingResults: Error: [Callstack] 0x00007ffb8b34274d UnrealEditor-Engine.dll!FBodyInstance::InitBody() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\PhysicsEngine\BodyInstance.cpp:1745]
[2025.11.10-15.23.09:160][253]PackagingResults: Error: [Callstack] 0x00007ffb8b342063 UnrealEditor-Engine.dll!FBodyInstance::InitBody() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\PhysicsEngine\BodyInstance.cpp:1708]
[2025.11.10-15.23.09:160][253]PackagingResults: Error: [Callstack] 0x00007ffb8a4ecb64 UnrealEditor-Engine.dll!UPrimitiveComponent::OnCreatePhysicsState() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Components\PrimitiveComponent.cpp:915]
[2025.11.10-15.23.09:161][253]PackagingResults: Error: [Callstack] 0x00007ffb8a638dae UnrealEditor-Engine.dll!UStaticMeshComponent::OnCreatePhysicsState() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Components\StaticMeshComponent.cpp:952]
[2025.11.10-15.23.09:161][253]PackagingResults: Error: [Callstack] 0x00007ffb8a399adc UnrealEditor-Engine.dll!UActorComponent::CreatePhysicsState() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Components\ActorComponent.cpp:2303]
[2025.11.10-15.23.09:161][253]PackagingResults: Error: [Callstack] 0x00007ffb8a3a7311 UnrealEditor-Engine.dll!UActorComponent::ExecuteRegisterEvents() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Components\ActorComponent.cpp:2389]
[2025.11.10-15.23.09:161][253]PackagingResults: Error: [Callstack] 0x00007ffb8a41a26a UnrealEditor-Engine.dll!UActorComponent::RegisterComponentWithWorld() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Components\ActorComponent.cpp:1918]
[2025.11.10-15.23.09:161][253]PackagingResults: Error: [Callstack] 0x00007ffb89b33c8f UnrealEditor-Engine.dll!AActor::IncrementalRegisterComponents() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Actor.cpp:6181]
[2025.11.10-15.23.09:161][253]PackagingResults: Error: [Callstack] 0x00007ffb8ac99435 UnrealEditor-Engine.dll!ULevel::IncrementalRegisterComponents() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Level.cpp:2001]
[2025.11.10-15.23.09:161][253]PackagingResults: Error: [Callstack] 0x00007ffb8ac99e04 UnrealEditor-Engine.dll!ULevel::IncrementalUpdateComponents() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Level.cpp:1865]
[2025.11.10-15.23.09:161][253]PackagingResults: Error: [Callstack] 0x00007ffb8acdaaf7 UnrealEditor-Engine.dll!ULevel::UpdateLevelComponents() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Level.cpp:1663]
[2025.11.10-15.23.09:161][253]PackagingResults: Error: [Callstack] 0x00007ffb8bf4c93b UnrealEditor-Engine.dll!UWorld::UpdateWorldComponents() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\World.cpp:2804]
[2025.11.10-15.23.09:183][254]PackagingResults: Error: [Callstack] 0x00007ffb86c806ef UnrealEditor-UnrealEd.dll!UEditorEngine::InitializePhysicsSceneForSaveIfNecessary() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorEngine.cpp:4320]
[2025.11.10-15.23.09:183][254]PackagingResults: Error: [Callstack] 0x00007ffb86c98e46 UnrealEditor-UnrealEd.dll!UEditorEngine::Save() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorEngine.cpp:4432]
[2025.11.10-15.23.09:183][254]PackagingResults: Error: [Callstack] 0x00007ffb869b9898 UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::SaveCookedPackage() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Cooker\CookSavePackage.cpp:126]
[2025.11.10-15.23.09:184][254]PackagingResults: Error: [Callstack] 0x00007ffb87ac22dc UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PumpRuntimeSaves() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:5053]
[2025.11.10-15.23.09:184][254]PackagingResults: Error: [Callstack] 0x00007ffb87ad1744 UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::TickMainCookLoop() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:1528]
[2025.11.10-15.23.09:184][254]PackagingResults: Error: [Callstack] 0x00007ffb87ad0ecc UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::TickCookByTheBook() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:1408]
[2025.11.10-15.23.09:184][254]PackagingResults: Error: [Callstack] 0x00007ffb86739940 UnrealEditor-UnrealEd.dll!UCookCommandlet::RunCookByTheBookCook() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:598]
[2025.11.10-15.23.09:184][254]PackagingResults: Error: [Callstack] 0x00007ffb866fa69a UnrealEditor-UnrealEd.dll!UCookCommandlet::CookByTheBook() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:550]
[2025.11.10-15.23.09:184][254]PackagingResults: Error: [Callstack] 0x00007ffb86716c83 UnrealEditor-UnrealEd.dll!UCookCommandlet::Main() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:269]
[2025.11.10-15.23.09:184][254]PackagingResults: Error: [Callstack] 0x00007ff7543a8fa0 UnrealEditor-Win64-DebugGame-Cmd.exe!FEngineLoop::PreInitPostStartupScreen() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:3860]
[2025.11.10-15.23.09:184][254]PackagingResults: Error: [Callstack] 0x00007ff75439e39c UnrealEditor-Win64-DebugGame-Cmd.exe!GuardedMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:143]
[2025.11.10-15.23.09:185][254]PackagingResults: Error: [Callstack] 0x00007ff75439e6ba UnrealEditor-Win64-DebugGame-Cmd.exe!GuardedMainWrapper() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:128]
[2025.11.10-15.23.09:185][254]PackagingResults: Error: [Callstack] 0x00007ff7543a209e UnrealEditor-Win64-DebugGame-Cmd.exe!LaunchWindowsStartup() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:282]
[2025.11.10-15.23.09:185][254]PackagingResults: Error: [Callstack] 0x00007ff7543b4e44 UnrealEditor-Win64-DebugGame-Cmd.exe!WinMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:339]
[2025.11.10-15.23.09:185][254]PackagingResults: Error: [Callstack] 0x00007ff7543b7472 UnrealEditor-Win64-DebugGame-Cmd.exe!__scrt_common_main_seh() [D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
[2025.11.10-15.23.09:185][254]PackagingResults: Error: [Callstack] 0x00007ffc17857374 KERNEL32.DLL!UnknownFunction []
[2025.11.10-15.23.09:185][254]PackagingResults: Error: [Callstack] 0x00007ffc184fcc91 ntdll.dll!UnknownFunction []
[2025.11.10-15.23.09:185][254]PackagingResults: Error: end: stack for UAT
vexe
November 11, 2025, 8:29pm
3
Found the issue in my case. There was an actor in one of the levels with GravitGroupIndex 10. You can write a little script to help you find these invalid values.
void UDTCheatManager::AliTesting()
{
TArray<UObject*> ActorList;
LoadBlueprintCDOsByType(AActor::StaticClass(), ActorList);
for(auto It : ActorList)
{
auto Actor = Cast<AActor>(It);
if (Actor)
{
for (auto Comp : Actor->GetComponents())
{
auto Primitive = Cast<UPrimitiveComponent>(Comp);
if (Primitive)
{
int Index = Primitive->BodyInstance.GravityGroupIndex;
if (Index >= 8)
{
UE_LOG(LogTemp, Error, TEXT("Object has invalid GravityGroupIndex %s"), *Actor->GetName());
}
}
}
}
}
}
I found mine finally, I had to find them manually but a single floor and wall tile had an index of 10 for some reason.
