Need help with project crashing at startup

Jacko.ando · May 20, 2025, 2:25am

Project crashes upon opening after reaching ~95% loaded, despite working not even a day ago . Crash report with debugging symbols reads as follows:

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffffffffffff

UnrealEditor_Core!_mi_heap_malloc_zero() [D:\build++UE5\Sync\Engine\Source\ThirdParty\mimalloc\2.0.0\src\alloc.c:147]
UnrealEditor_Core!FMallocMimalloc::Realloc() [D:\build++UE5\Sync\Engine\Source\Runtime\Core\Private\HAL\MallocMimalloc.cpp:155]
UnrealEditor_Core!FMemory::Realloc() [D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\HAL\FMemory.inl:134]
UnrealEditor_Core!TSizedHeapAllocator<32,FMemory>::ForAnyElementType::ResizeAllocation() [D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\ContainerAllocationPolicies.h:746]
UnrealEditor_Core!TArray<wchar_t,TSizedDefaultAllocator<32> >::ResizeTo() [D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h:3174]
UnrealEditor_Core!operator<<() [D:\build++UE5\Sync\Engine\Source\Runtime\Core\Private\Containers\String.cpp.inl:1809]
UnrealEditor_Engine!UEdGraphPin::Serialize() [D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\EdGraph\EdGraphPin.cpp:1710]
UnrealEditor_Engine!UEdGraphPin::SerializePin() [D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\EdGraph\EdGraphPin.cpp:2119]
UnrealEditor_Engine!UEdGraphPin::SerializePinArray() [D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\EdGraph\EdGraphPin.cpp:1922]
UnrealEditor_Engine!UEdGraphNode::Serialize() [D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\EdGraph\EdGraphNode.cpp:258]
UnrealEditor_BlueprintGraph!UK2Node::Serialize() [D:\build++UE5\Sync\Engine\Source\Editor\BlueprintGraph\Private\K2Node.cpp:135]
UnrealEditor_BlueprintGraph!UK2Node_CallFunction::Serialize() [D:\build++UE5\Sync\Engine\Source\Editor\BlueprintGraph\Private\K2Node_CallFunction.cpp:2417]
UnrealEditor_CoreUObject!FLinkerLoad::Preload() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:4770]
UnrealEditor_CoreUObject!FAsyncPackage2::PreloadLinkerLoadExports() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:6025]
UnrealEditor_CoreUObject!FAsyncPackage2::Event_PreloadLinkerLoadExports() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:6408]
UnrealEditor_CoreUObject!FEventLoadNode2::Execute() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:4960]
UnrealEditor_CoreUObject!FAsyncLoadEventQueue2::ExecuteSyncLoadEvents() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:5167]
UnrealEditor_CoreUObject!FAsyncLoadingThread2::ProcessAsyncLoadingFromGameThread() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:8091]
UnrealEditor_CoreUObject!FAsyncLoadingThread2::TickAsyncLoadingFromGameThread() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:8440]
UnrealEditor_CoreUObject!FAsyncLoadingThread2::FlushLoading() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:9923]
UnrealEditor_CoreUObject!FlushAsyncLoading() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncPackageLoader.cpp:327]
UnrealEditor_CoreUObject!FlushAsyncLoading() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncPackageLoader.cpp:296]
UnrealEditor_CoreUObject!LoadPackageInternal() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1757]
UnrealEditor_CoreUObject!LoadPackage() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:2121]
UnrealEditor_CoreUObject!LoadPackage() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:2097]
UnrealEditor_CoreUObject!StaticLoadObjectInternal() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1420]
UnrealEditor_CoreUObject!StaticLoadObject() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1466]
UnrealEditor_CoreUObject!FObjectPropertyBase::FindImportedObject() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\PropertyBaseObject.cpp:592]
UnrealEditor_CoreUObject!FObjectPropertyBase::ParseObjectPropertyValue() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\PropertyBaseObject.cpp:394]
UnrealEditor_CoreUObject!FObjectPropertyBase::ImportText_Internal() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\PropertyBaseObject.cpp:426]
UnrealEditor_CoreUObject!FObjectProperty::ImportText_Internal() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\PropertyObject.cpp:330]
UnrealEditor_CoreUObject!FClassProperty::ImportText_Internal() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\PropertyClass.cpp:114]
UnrealEditor_CoreUObject!FArrayProperty::ImportTextInnerItem() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\PropertyArray.cpp:1054]
UnrealEditor_CoreUObject!FArrayProperty::ImportText_Internal() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\PropertyArray.cpp:1002]
UnrealEditor_UnrealEd!FBlueprintEditorUtils::PropertyValueFromString_Direct() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Kismet2\BlueprintEditorUtils.cpp:9284]
UnrealEditor_UnrealEd!UUserDefinedStructEditorData::ReinitializeDefaultInstance() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\UserDefinedStructEditorData.cpp:252]
UnrealEditor_CoreUObject!UUserDefinedStruct::Serialize() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\StructUtils\UserDefinedStruct.cpp:133]
UnrealEditor_CoreUObject!UUserDefinedStruct::Serialize() [D:\build++UE5\Sync\Engine\Intermediate\Build\Win64\UnrealEditor\Inc\CoreUObject\UHT\UserDefinedStruct.gen.cpp:208]
UnrealEditor_CoreUObject!FLinkerLoad::Preload() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:4770]
UnrealEditor_CoreUObject!UUserDefinedStruct::RecursivelyPreload() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\StructUtils\UserDefinedStruct.cpp:387]
UnrealEditor_CoreUObject!PreloadInnerStructMembers() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\PropertyStruct.cpp:30]
UnrealEditor_CoreUObject!FStructProperty::Serialize() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\PropertyStruct.cpp:242]
UnrealEditor_CoreUObject!UStruct::SerializeProperties() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:2176]
UnrealEditor_CoreUObject!UStruct::Serialize() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:2298]
UnrealEditor_CoreUObject!UClass::Serialize() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:5593]
UnrealEditor_Engine!UBlueprintGeneratedClass::Serialize() [D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\BlueprintGeneratedClass.cpp:2536]
UnrealEditor_CoreUObject!FLinkerLoad::Preload() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:4770]
UnrealEditor_CoreUObject!FLinkerLoad::CreateExport() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:5615]
UnrealEditor_CoreUObject!FLinkerLoad::CreateImport() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:5799]
UnrealEditor_CoreUObject!FLinkerLoad::ResolveDependencyPlaceholder() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Blueprint\BlueprintSupport.cpp:1769]
UnrealEditor_CoreUObject!FLinkerLoad::ResolveDeferredDependencies() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Blueprint\BlueprintSupport.cpp:1595]
UnrealEditor_CoreUObject!FLinkerLoad::Preload() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:4824]
UnrealEditor_CoreUObject!FLinkerLoad::CreateExport() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:5615]
UnrealEditor_CoreUObject!FLinkerLoad::CreateImport() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:5799]
UnrealEditor_CoreUObject!FLinkerLoad::ResolveDependencyPlaceholder() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Blueprint\BlueprintSupport.cpp:1769]
UnrealEditor_CoreUObject!FLinkerLoad::ResolveDeferredDependencies() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Blueprint\BlueprintSupport.cpp:1595]
UnrealEditor_CoreUObject!FLinkerLoad::Preload() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:4824]
UnrealEditor_CoreUObject!FLinkerLoad::CreateExport() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:5615]
UnrealEditor_CoreUObject!FLinkerLoad::CreateImport() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:5799]
UnrealEditor_CoreUObject!FLinkerLoad::ResolveDependencyPlaceholder() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Blueprint\BlueprintSupport.cpp:1769]
UnrealEditor_CoreUObject!FLinkerLoad::ResolveDeferredDependencies() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Blueprint\BlueprintSupport.cpp:1595]
UnrealEditor_CoreUObject!FLinkerLoad::Preload() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:4824]
UnrealEditor_CoreUObject!FLinkerLoad::CreateExport() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\LinkerLoad.cpp:5615]
UnrealEditor_CoreUObject!FAsyncPackage2::CreateLinkerLoadExports() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:6152]
UnrealEditor_CoreUObject!FAsyncPackage2::Event_CreateLinkerLoadExports() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:6336]
UnrealEditor_CoreUObject!FEventLoadNode2::Execute() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:4960]
UnrealEditor_CoreUObject!FAsyncLoadEventQueue2::ExecuteSyncLoadEvents() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:5167]
UnrealEditor_CoreUObject!FAsyncLoadingThread2::ProcessAsyncLoadingFromGameThread() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:8091]
UnrealEditor_CoreUObject!FAsyncLoadingThread2::TickAsyncLoadingFromGameThread() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:8440]
UnrealEditor_CoreUObject!FAsyncLoadingThread2::FlushLoading() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading2.cpp:9923]
UnrealEditor_CoreUObject!FlushAsyncLoading() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncPackageLoader.cpp:327]
UnrealEditor_CoreUObject!FlushAsyncLoading() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncPackageLoader.cpp:296]
UnrealEditor_CoreUObject!LoadPackageInternal() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:1757]
UnrealEditor_CoreUObject!LoadPackage() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:2121]
UnrealEditor_CoreUObject!LoadPackage() [D:\build++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:2097]
UnrealEditor_UnrealEd!UEditorEngine::Map_Load() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp:2603]
UnrealEditor_UnrealEd!UEditorEngine::HandleMapCommand() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp:6213]
UnrealEditor_UnrealEd!UEditorEngine::Exec_Editor() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp:5674]
UnrealEditor_Core!FExec::Exec() [D:\build++UE5\Sync\Engine\Source\Runtime\Core\Private\Misc\Exec.cpp:18]
UnrealEditor_Engine!UEngine::Exec() [D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\UnrealEngine.cpp:5027]
UnrealEditor_UnrealEd!UUnrealEdEngine::Exec() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdSrv.cpp:662]
UnrealEditor_UnrealEd!FEditorFileUtils::LoadMap() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\FileHelpers.cpp:2952]
UnrealEditor_UnrealEd!FEditorFileUtils::LoadDefaultMapAtStartup() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\FileHelpers.cpp:4958]
UnrealEditor_UnrealEd!FUnrealEdMisc::OnInit() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdMisc.cpp:375]
UnrealEditor_UnrealEd!EditorInit() [D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdGlobals.cpp:137]
UnrealEditor!GuardedMain() [D:\build++UE5\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:166]
UnrealEditor!GuardedMainWrapper() [D:\build++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:123]
UnrealEditor!LaunchWindowsStartup() [D:\build++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:277]
UnrealEditor!WinMain() [D:\build++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:317]
UnrealEditor!__scrt_common_main_seh() [D:\a_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
kernel32
ntdll

Will verify UE 5.5.4 files and maybe try regenerating project files as found on this video https://www.youtube.com/watch?v=XpYZytx_so4.

Ivan3z · May 20, 2025, 3:42am

Are you serializing something in a constructor?

Seems it crash while allocating memory for some serialization

Jacko.ando · May 20, 2025, 8:54am

Yes it seems to chuck a few serilization errors at me, unsure as to why they decide to crash however.

I’ve verified my UE 5.5.4 installment and still receiving the crash error but with regards to regenerating project files it also seems that I’m unable to select “Generate Visual Studio project files” giving me an error message “This project does not have any source code. You need to add C++ source files to the project from the Editor before you can generate project files.”

Edit: Went ahead and deleted the Dedicated Data Cache, Intermediate, and Saved files as those generate anyhow upon startup and seemingly a new crash report is generating each startup attempt… Welp at least I was able to migrate my assets to a new project and nothing major was lost

3dRaven · May 20, 2025, 10:16am

Knowing Unreal it’s probably a corrupted blueprint struct that was added to a function via a pin.

Your code seems to be passing the null pointer exception point, so the passed in variable is valid, but fails while trying to access memory. Hence could point towards corruption.

Did you make all of your base structs in c++ or did you go the quick route of blueprint versions?

Jacko.ando · May 20, 2025, 10:54am

From memory most structs would’ve been blueprint instead of C++

Ivan3z · May 20, 2025, 10:58am

Blueprint are nice for fast test and fast debugging…
But they are very problematics.

Belive me… you want to work with C++

Jacko.ando · May 20, 2025, 11:03am

Following along with your steps, everything you’ve linked was usable however the Catharsis.cpp linked is sending me to a https.

Ivan3z · May 20, 2025, 11:06am

I see it… for some reason chrome decided it is a web site LOL…

Copy and paste the content in a new file and remane and edit like i sayd you

also there is a misterius file “TutorialCpp1.h” → i don’t know how arrive it there XD… it is not necessay

Edited:

The real name of “TutorialCpp1.h” is → “Catharsis.h”

I Have not idea how was changed the name of this file…
This web must to have bugs too…
Epic always have a new bug for me everyday… it is awesome

Jacko.ando · May 20, 2025, 11:59am

Thanks for the clarification and helpful replies. I’ve gotten everything in order and running the .bat file is telling me:

Creating makefile for TechnophobiaEditor (no existing makefile)
Total execution time: 0.44 seconds
Platform Win64 is not a valid platform to build. Check that the SDK is installed properly and that you have the necessary platform support files (DataDrivenPlatformInfo.ini, SDK.json, etc).

Similarly, the Generate Visual Studio project files option found on the .uproject is telling me:

Some Platforms were skipped due to invalid SDK setup: Win64.
See the log file for detailed information

Generating VisualStudio project files:
Discovering modules, targets and source code for project...
No valid Visual C++ toolchain was found (minimum version 14.38.33130, preferred version 14.38.33130). Please download and install Visual Studio 2022 17.8 or later and verify that the "MSVC v143 - VS 2022 C++ x64/x86 build tools (v14.38-17.8)" component is selected in the Visual Studio 2022 installation options.
Total execution time: 7.67 seconds
Visual Studio 2022 x64 must be installed in order to build this target.

So now I need to figure out why my Visual Studio isn’t cooperating with Unreal. I’ll try a clean VS install with the appropriate extensions. I am however a bit concerned with Win64 SDK being a non-viable building platform, should this be worrying?

Ivan3z · May 20, 2025, 12:13pm

Yes… that is exactly the the problem…

Wait a minute while i looking for the SDK version that works

Ivan3z · May 20, 2025, 12:24pm

I think is this

22621.1778.230511-2102.ni_release_svc_prod3_WindowsSDK (2025).iso

this is the last one i have

i was lookingt there is a lot of folders

C:\Program Files (x86)\Microsoft SDKs\Windows Kits\10\ExtensionSDKs

Ivan3z · May 20, 2025, 12:30pm

i think i found it.

Dowload and intall this SDK version

TargetPlatformMinVersion="10.0.10240.0"

Jacko.ando · May 20, 2025, 3:28pm

Alright, some time later with crappy Aussie wifi and the reinstall of Windows SDK and VS 2022 has worked with the .bat file, allowing the Generate Visual Studio project files option to successfully generate and regenerate.

This unfortunately still won’t recover the previous project as it still crashes on startup, my suspicion is that the corrupted structs/files will have to be identified and removed if that is possible. Or perhaps this is the start of my C++ life, who knows.

Ivan3z · May 20, 2025, 3:43pm

i also leave the blueprint for something like that.

¿Do you have code in the CONSTRUCTOR SCRIPT?
That was my problem… access to an invallid reference in the constructor script of a bllueprint…

if so… delete that blueprint and the engine will work…
but if it is a imortant blueprint all your code will be broke

that never happend with C++

3dRaven · May 20, 2025, 7:11pm

This thread mirrors for the most part the errors when it comes to structs (looking at parts of the error report). The op had a corrupt asset

Be cautious with making blueprint structs in the future. They have a tendency to break when you start introducing c++ (launching a project not from the ide can be enough to have them have a catastrophic failure).

Most forum veterans will tell you to keep them in c++ if it’s not a pure bp project.

Another area where the project can break is if the parent c++ class of a bp goes missing (you can for instance rename it in pure c++ then without a manual re-director it will be broken)

Ivan3z · May 21, 2025, 2:57pm

@Jacko.ando do what 3DRaven says

When I migrated from UE4.27 to UE5, all my bluprint structures became “corrupt”… they worked but couldn’t be edited anymore. Something like this will never happen with C++.

I use blueprints only for data… only for deriving from C++ classes

If you change the class name, simply reparent it with another parent temporarily (for example, with the actor class)… this will avoid redirector problems.

If you have a variable declared in another class (an object of the class you renamed), change the name of the variable as well. Because the blueprint has memory (or something like that)… And the bluprint will appear to be corrupted. The only way to fix it is to change the variable name.

If you have problems with HOT RELOAD, close the editor, delete the temporary files and compile with the editor closed.

Converting all my blueprints to C++ was hard work… but definitely worth it. A lot of problems disappeared. And other new ones appeared XD. But they are definitely easier to fix.

Good luck on your new start in C++