Assertion failed: PIEInstanceID != INDEX_NONE [File:C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\LazyObjectPtr.cpp] [Line: 22] UnrealEditor_CoreUObject!FLazyObjectPtr::PossiblySerializeObjectGuid() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\LazyObjectPtr.cpp:150] UnrealEditor_CoreUObject!UObject::Serialize() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\Obj.cpp:1461] UnrealEditor_CoreUObject!UObject::Serialize() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\Obj.cpp:1320] UnrealEditor_Engine!AActor::Serialize() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\Engine\Private\Actor.cpp:838] UnrealEditor_Landscape!ALandscapeProxy::Serialize() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\Landscape\Private\Landscape.cpp:2244] UnrealEditor_CoreUObject!FLinkerLoad::Preload() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:4388] UnrealEditor_CoreUObject!EndLoad() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1658] UnrealEditor_CoreUObject!<lambda_c8710bcd35c9e247c18bb173ed0f9483>::operator()() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1264] UnrealEditor_CoreUObject!LoadPackageInternal() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1366] UnrealEditor_CoreUObject!LoadPackage() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1520] UnrealEditor_CoreUObject!LoadPackage() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1500] UnrealEditor_Engine!UEngine::LoadMap() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\Engine\Private\UnrealEngine.cpp:13983] UnrealEditor_Engine!UEngine::Browse() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\Engine\Private\UnrealEngine.cpp:13412] UnrealEditor_Engine!UEngine::TickWorldTravel() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Runtime\Engine\Private\UnrealEngine.cpp:13610] UnrealEditor_UnrealEd!UEditorEngine::Tick() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Editor\UnrealEd\Private\EditorEngine.cpp:1751] UnrealEditor_UnrealEd!UUnrealEdEngine::Tick() [C:\Jenkins_node\workspace\UnrealEngine\Engine\Source\Editor\UnrealEd\Private\UnrealEdEngine.cpp:474]
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-156921 in the post.