Unreal Engine 4.26.1 crashes when compiling blueprint

My editor crashes nearly every time I compile certain blueprint classes. There’s three blueprint classes in particular that the editor seems to take an issue with, when I start up the editor I can usually compile one or two of them without a crash, but when I try to compile the third one (regardless of which of the three classes I leave to compile last), I get this message:

(I tried reading the referenced engine source code but since I’m not knowledgeable in serialization, there was no useful insight I could gain by myself.)

Fatal error!

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000000100000019

0x00007ff849c6fac8 UE4Editor-CoreUObject.dll!FPropertyProxyArchive::operator<<() [D:\Build\++UE4\Sync\Engine\Source\Runtime\CoreUObject\Public\UObject\PropertyProxyArchive.h:46]
0x00007ff849d824ba UE4Editor-CoreUObject.dll!UStruct::SerializeExpr() [D:\Build\++UE4\Sync\Engine\Source\Runtime\CoreUObject\Public\UObject\ScriptSerialization.h:316]
0x00007ff849d8189b UE4Editor-CoreUObject.dll!UStruct::SerializeExpr() [D:\Build\++UE4\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:2145]
0x00007ff849d7d04a UE4Editor-CoreUObject.dll!UStruct::Serialize() [D:\Build\++UE4\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:1944]
0x00007ff849d7c47e UE4Editor-CoreUObject.dll!UFunction::Serialize() [D:\Build\++UE4\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:5601]
0x00007ff849c17c36 UE4Editor-CoreUObject.dll!FArchiveReplaceObjectRefBase::SerializeObject() [D:\Build\++UE4\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\ArchiveUObject.cpp:243]
0x00007ff82e6b5f65 UE4Editor-UnrealEd.dll!FArchiveReplaceFieldReferences::FArchiveReplaceFieldReferences() [D:\Build\++UE4\Sync\Engine\Source\Editor\UnrealEd\Private\Kismet2\KismetReinstanceUtilities.cpp:864]
0x00007ff82e722b4d UE4Editor-UnrealEd.dll!FBlueprintCompileReinstancer::UpdateBytecodeReferences() [D:\Build\++UE4\Sync\Engine\Source\Editor\UnrealEd\Private\Kismet2\KismetReinstanceUtilities.cpp:997]
0x00007ff844347d5c UE4Editor-Kismet.dll!FBlueprintCompilationManagerImpl::ReinstanceBatch() [D:\Build\++UE4\Sync\Engine\Source\Editor\Kismet\Private\BlueprintCompilationManager.cpp:2020]
0x00007ff8442f1282 UE4Editor-Kismet.dll!FBlueprintCompilationManagerImpl::FlushCompilationQueueImpl() [D:\Build\++UE4\Sync\Engine\Source\Editor\Kismet\Private\BlueprintCompilationManager.cpp:1395]
0x00007ff844295eaf UE4Editor-Kismet.dll!FBlueprintCompilationManagerImpl::CompileSynchronouslyImpl() [D:\Build\++UE4\Sync\Engine\Source\Editor\Kismet\Private\BlueprintCompilationManager.cpp:277]
0x00007ff844295bf1 UE4Editor-Kismet.dll!FBlueprintCompilationManager::CompileSynchronously() [D:\Build\++UE4\Sync\Engine\Source\Editor\Kismet\Private\BlueprintCompilationManager.cpp:3090]
0x00007ff82e6d5efe UE4Editor-UnrealEd.dll!FKismetEditorUtilities::CompileBlueprint() [D:\Build\++UE4\Sync\Engine\Source\Editor\UnrealEd\Private\Kismet2\Kismet2.cpp:754]
0x00007ff84439ff6c UE4Editor-Kismet.dll!FBlueprintEditor::Compile() [D:\Build\++UE4\Sync\Engine\Source\Editor\Kismet\Private\BlueprintEditor.cpp:3627]
0x00007ff8443bd576 UE4Editor-Kismet.dll!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,void __cdecl(void),FDefaultDelegateUserPolicy>::ExecuteIfSafe() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:307]
0x00007ff846c00098 UE4Editor-Slate.dll!FUICommandList::ExecuteAction() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Slate\Private\Framework\Commands\UICommandList.cpp:102]
0x00007ff846cef3a2 UE4Editor-Slate.dll!SToolBarButtonBlock::OnClicked() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Slate\Private\Framework\MultiBox\SToolBarButtonBlock.cpp:301]
0x00007ff846ccbd67 UE4Editor-Slate.dll!TBaseSPMethodDelegateInstance<0,SToolBarButtonBlock,0,FReply __cdecl(void),FDefaultDelegateUserPolicy>::Execute() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:290]
0x00007ff846d685fe UE4Editor-Slate.dll!SButton::ExecuteOnClick() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Slate\Private\Widgets\Input\SButton.cpp:385]
0x00007ff846d8077e UE4Editor-Slate.dll!SButton::OnMouseButtonUp() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Slate\Private\Widgets\Input\SButton.cpp:304]
0x00007ff846bc46be UE4Editor-Slate.dll!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_cc5aea9e7377b04ce85c30c65ec3889b> >() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:378]
0x00007ff846c47f54 UE4Editor-Slate.dll!FSlateApplication::RoutePointerUpEvent() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:4815]
0x00007ff846c30367 UE4Editor-Slate.dll!FSlateApplication::ProcessMouseButtonUpEvent() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:5356]
0x00007ff846c23642 UE4Editor-Slate.dll!FSlateApplication::OnMouseUp() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:5321]
0x00007ff86193bca5 UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessDeferredMessage() [D:\Build\++UE4\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:2174]
0x00007ff861929197 UE4Editor-ApplicationCore.dll!FWindowsApplication::DeferMessage() [D:\Build\++UE4\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:2638]
0x00007ff86193e379 UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessMessage() [D:\Build\++UE4\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:1042]
0x00007ff861924310 UE4Editor-ApplicationCore.dll!FWindowsApplication::AppWndProc() [D:\Build\++UE4\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:874]
0x00007ff88e3ae858 USER32.dll!UnknownFunction []
0x00007ff88e3ae299 USER32.dll!UnknownFunction []
0x00007ff86193f904 UE4Editor-ApplicationCore.dll!FWindowsPlatformApplicationMisc::PumpMessages() [D:\Build\++UE4\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsPlatformApplicationMisc.cpp:130]
0x00007ff6563c8857 UE4Editor.exe!FEngineLoop::Tick() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:4748]
0x00007ff6563e11ac UE4Editor.exe!GuardedMain() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:169]
0x00007ff6563e128a UE4Editor.exe!GuardedMainWrapper() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:137]
0x00007ff6563f52ed UE4Editor.exe!WinMain() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:268]
0x00007ff6563f801a UE4Editor.exe!__scrt_common_main_seh() [d:\agent\_work\5\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
0x00007ff88e567034 KERNEL32.DLL!UnknownFunction []
0x00007ff88ea42651 ntdll.dll!UnknownFunction []

Hello

I’m also experiencing a similar problem. I cant seem to pin point which blueprint is causing this issue. Did you manage to find out which blueprint was causing the problem? If so, do you mind sharing the procedure you have followed?

I’m experiencing this problem in 4.26.1 and 4.26.2 .

UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error: begin: stack for UAT
UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error: === Handled ensure: ===
UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error:
UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error: Ensure condition failed: !FPackageName::IsShortPackageName(Path) [File:D:/Build/++UE4/Sync/Engine/Source/Runtime/CoreUObject/Private/UObject/SoftObjectPath.cpp] [Line: 79]
UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error: Cannot create SoftObjectPath with short package name ‘NewEnumerator0’! You must pass in fully qualified package names
UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error: Stack:
UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error: [Callstack] 0x00007ffcbeda1909 UE4Editor-CoreUObject.dll!DispatchCheckVerify >() .
.
.
.
.[d:\agent_work\5\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error: [Callstack] 0x00007ffd28447034 KERNEL32.DLL!UnknownFunction []
UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error: [Callstack] 0x00007ffd29e62651 ntdll.dll!UnknownFunction []
UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogOutputDevice: Error: end: stack for UAT