Unreal Engine Issues and Bug Tracker (UE-94970)

Description

REGRESSION: Issue does not occur in 4.24

Crash occurs when the user changes a blueprint TMap value from Vector to Vector4 and then compiles the blueprint.

This seems to only occur with TMaps, as I wasn't able to reproduce this with other container types. I also wasn't able to reproduce this by changing the Vector to an Int, or from Int to Vector4.

Steps to Reproduce

Download and extract the attached project.
Open the project in editor.
Open TestBP.
Select the variable TestMap.
Change the Value from Vector to Vector4
Compile.

RESULT

Crash

Callstack

Assertion failed: Tag.Size == Loaded [File:D:/Build/++UE4+Licensee/Sync/Engine/Source/Runtime/CoreUObject/Private/UObject/Class.cpp] [Line: 1478] 

KERNELBASE.dll!UnknownFunction []
UE4Editor-Core.dll!ReportAssert() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Private\Windows\WindowsPlatformCrashContext.cpp:1541]
UE4Editor-Core.dll!FWindowsErrorOutputDevice::Serialize() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Private\Windows\WindowsErrorOutputDevice.cpp:78]
UE4Editor-Core.dll!FOutputDevice::LogfImpl() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Private\Misc\OutputDevice.cpp:61]
UE4Editor-Core.dll!AssertFailedImplV() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Private\Misc\AssertionMacros.cpp:100]
UE4Editor-Core.dll!FDebug::CheckVerifyFailedImpl() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Private\Misc\AssertionMacros.cpp:450]
UE4Editor-CoreUObject.dll!UStruct::SerializeVersionedTaggedProperties() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:1478]
UE4Editor-CoreUObject.dll!UStruct::SerializeTaggedProperties() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:1266]
UE4Editor-CoreUObject.dll!UObject::SerializeScriptProperties() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Obj.cpp:1438]
UE4Editor-CoreUObject.dll!UObject::Serialize() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Obj.cpp:1358]
UE4Editor-CoreUObject.dll!UObject::Serialize() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Obj.cpp:1247]
UE4Editor-Engine.dll!AActor::Serialize() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Engine\Private\Actor.cpp:665]
UE4Editor-Engine.dll!UEngine::CopyPropertiesForUnrelatedObjects() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Engine\Private\UnrealEngine.cpp:14329]
UE4Editor-UnrealEd.dll!FBlueprintCompileReinstancer::CopyPropertiesForUnrelatedObjects() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\UnrealEd\Private\Kismet2\KismetReinstanceUtilities.cpp:2387]
UE4Editor-Kismet.dll!FBlueprintCompilationManagerImpl::ReinstanceBatch() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\Kismet\Private\BlueprintCompilationManager.cpp:2013]
UE4Editor-Kismet.dll!FBlueprintCompilationManagerImpl::FlushCompilationQueueImpl() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\Kismet\Private\BlueprintCompilationManager.cpp:1362]
UE4Editor-Kismet.dll!FBlueprintCompilationManagerImpl::CompileSynchronouslyImpl() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\Kismet\Private\BlueprintCompilationManager.cpp:263]
UE4Editor-Kismet.dll!FBlueprintCompilationManager::CompileSynchronously() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\Kismet\Private\BlueprintCompilationManager.cpp:3040]
UE4Editor-UnrealEd.dll!FKismetEditorUtilities::CompileBlueprint() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\UnrealEd\Private\Kismet2\Kismet2.cpp:754]
UE4Editor-Kismet.dll!FBlueprintEditor::Compile() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\Kismet\Private\BlueprintEditor.cpp:3474]
UE4Editor-Kismet.dll!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,void __cdecl(void)>::ExecuteIfSafe() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:374]
UE4Editor-Slate.dll!FUICommandList::ExecuteAction() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Slate\Private\Framework\Commands\UICommandList.cpp:102]
UE4Editor-Slate.dll!SToolBarButtonBlock::OnClicked() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Slate\Private\Framework\MultiBox\SToolBarButtonBlock.cpp:302]
UE4Editor-Slate.dll!TBaseSPMethodDelegateInstance<0,SToolBarButtonBlock,0,FReply __cdecl(void)>::Execute() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:298]
UE4Editor-Slate.dll!SButton::ExecuteOnClick() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Slate\Private\Widgets\Input\SButton.cpp:385]
UE4Editor-Slate.dll!SButton::OnMouseButtonUp() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Slate\Private\Widgets\Input\SButton.cpp:304]
UE4Editor-Slate.dll!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_cc5aea9e7377b04ce85c30c65ec3889b> >() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:372]
UE4Editor-Slate.dll!FSlateApplication::RoutePointerUpEvent() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:4675]
UE4Editor-Slate.dll!FSlateApplication::ProcessMouseButtonUpEvent() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:5198]
UE4Editor-Slate.dll!FSlateApplication::OnMouseUp() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:5166]
UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessDeferredMessage() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:2133]
UE4Editor-ApplicationCore.dll!FWindowsApplication::DeferMessage() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:2585]
UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessMessage() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:1809]
UE4Editor-ApplicationCore.dll!FWindowsApplication::AppWndProc() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:852]
USER32.dll!UnknownFunction []
USER32.dll!UnknownFunction []
UE4Editor-ApplicationCore.dll!FWindowsPlatformApplicationMisc::PumpMessages() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsPlatformApplicationMisc.cpp:130]
UE4Editor.exe!FEngineLoop::Tick() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:4762]
UE4Editor.exe!GuardedMain() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:169]
UE4Editor.exe!GuardedMainWrapper() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:137]
UE4Editor.exe!WinMain() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:268]
UE4Editor.exe!__scrt_common_main_seh() [d:\agent\_work\5\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
KERNEL32.DLL!UnknownFunction []
ntdll.dll!UnknownFunction []

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Fixed

Component	UE - Foundation - Core - UObject
Affects Versions	4.25, 4.26
Target Fix	4.27

Fix Commit	15887391
Main Commit	15887391

Created	Jun 29, 2020
Resolved	Apr 1, 2021
Updated	Apr 28, 2021

UE-94970

Crash compiling a blueprint after changing a TMap value from Vector to Vector4

Crash compiling a blueprint after changing a TMap value from Vector to Vector4

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