Error on upgrading from UE4 World Composition to UE5 World Partition: Assertion failed: InActor->IsPackageExternal() [...] WorldPartition\WorldPartitionActorDesc.cpp] [Line: 85]

Hello!
I’ve been trying to convert a world I have in Unreal 4’s World Composition to the new World Partition in Unreal Engine 5.3. I’m doing it via console, but every time I run the console, it starts but after a little while, it crashes with this error:

Assertion failed: InActor->IsPackageExternal() [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionActorDesc.cpp] [Line: 85]

UnrealEditor_Engine!FWorldDataLayersActorDesc::Init() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\DataLayer\WorldDataLayersActorDesc.cpp:208]
UnrealEditor_Engine!AActor::CreateActorDesc() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\ActorEditor.cpp:1123]
UnrealEditor_Engine!FWorldPartitionActorViewProxy::FWorldPartitionActorViewProxy() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionActorDescViewProxy.cpp:19]
UnrealEditor_DataLayerEditor!UDataLayerEditorSubsystem::PassDataLayersFilter() [D:\build\++UE5\Sync\Engine\Source\Editor\DataLayerEditor\Private\DataLayer\DataLayerEditorSubsystem.cpp:1157]
UnrealEditor_DataLayerEditor!`UDataLayerEditorSubsystem::Initialize'::`2'::FDataLayerActorDescFilter::PassFilter() [D:\build\++UE5\Sync\Engine\Source\Editor\DataLayerEditor\Private\DataLayer\DataLayerEditorSubsystem.cpp:212]
UnrealEditor_Engine!IWorldPartitionActorLoaderInterface::ILoaderAdapter::ShouldActorBeLoaded() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionActorLoaderInterface.cpp:259]
UnrealEditor_Engine!`IWorldPartitionActorLoaderInterface::ILoaderAdapter::RefreshLoadedState'::`8'::<lambda_1>::operator()() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionActorLoaderInterface.cpp:141]
UnrealEditor_Engine!`ILoaderAdapterSpatial::HandleIntersectingContainer'::`2'::<lambda_1>::operator()() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\LoaderAdapter\LoaderAdapterSpatial.cpp:42]
UnrealEditor_Engine!UWorldPartitionEditorSpatialHash::ForEachIntersectingActor() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionEditorSpatialHash.cpp:331]
UnrealEditor_Engine!ILoaderAdapterSpatial::HandleIntersectingContainer() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\LoaderAdapter\LoaderAdapterSpatial.cpp:34]
UnrealEditor_Engine!ILoaderAdapterSpatial::ForEachActor() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\LoaderAdapter\LoaderAdapterSpatial.cpp:22]
UnrealEditor_Engine!IWorldPartitionActorLoaderInterface::ILoaderAdapter::RefreshLoadedState() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionActorLoaderInterface.cpp:154]
UnrealEditor_Engine!IWorldPartitionActorLoaderInterface::ILoaderAdapter::Load() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionActorLoaderInterface.cpp:50]
UnrealEditor_Engine!UWorldPartition::Initialize() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartition.cpp:692]
UnrealEditor_Engine!ULevel::OnLevelLoaded() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Level.cpp:3019]
UnrealEditor_Engine!UWorld::InitWorld() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\World.cpp:2209]
UnrealEditor_UnrealEd!UWorldPartitionConvertCommandlet::InitWorld() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Commandlets\WorldPartitionConvertCommandlet.cpp:218]
UnrealEditor_UnrealEd!UWorldPartitionConvertCommandlet::Main() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Commandlets\WorldPartitionConvertCommandlet.cpp:875]
UnrealEditor!FEngineLoop::PreInitPostStartupScreen() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:4136]
UnrealEditor!GuardedMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:140]
UnrealEditor!GuardedMainWrapper() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:118]
UnrealEditor!LaunchWindowsStartup() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:258]
UnrealEditor!WinMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:298]
UnrealEditor!__scrt_common_main_seh() [D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
kernel32
ntdll

I tried removing the lines on my DefaultEngine.ini related to the start maps already since it seemed to be one of the solutions people found. But that didn’t work.

Thank you very much!

were you able to solve it