After upgrading to 4.7, the editor crashes while Hot Compiling

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1

After upgrading my project to 4.7, every time I compile the project in Visual Studio - even though it compiled sucessfully - the editor compiling progress bar never goes past 100%, eventually crashing with the following reoirt data:

Fatal error!

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x000007a2

UE4Editor-Engine.dll!AActor::ExecuteConstruction() (0x00007fff7eca079f) + 24 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\actorconstruction.cpp:512]
UE4Editor-Engine.dll!AActor::RerunConstructionScripts() (0x00007fff7ece6e4a) + 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\actorconstruction.cpp:422]
UE4Editor-UnrealEd.dll!FBlueprintCompileReinstancer::ReplaceInstancesOfClass() (0x00007fff7d8d2cba) + 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:926]
UE4Editor-UnrealEd.dll!FBlueprintCompileReinstancer::ReinstanceObjects() (0x00007fff7d8ca97a) + 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:366]
UE4Editor-HotReload.dll!FHotReloadModule::ReinstanceClass() (0x00007fff7479fdee) + 13 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\developer\hotreload\private\hotreload.cpp:849]
UE4Editor-CoreUObject.dll!UClassReplaceHotReloadClasses() (0x00007fff8e2e2453) + 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\coreuobject\private\uobject\uobjectbase.cpp:703]
UE4Editor-CoreUObject.dll!TBaseStaticDelegateInstance<void __cdecl(void)>::ExecuteIfSafe() (0x00007fff8e183c97) + 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:921]
UE4Editor-Core.dll!TBaseMulticastDelegate<void>::Broadcast() (0x00007fff81456fb5) + 11 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\public\delegates\delegatesignatureimpl_variadics.inl:1030]
UE4Editor-Core.dll!FModuleManager::LoadModuleWithFailureReason() (0x00007fff816031a2) + 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\private\modules\modulemanager.cpp:359]
UE4Editor-Core.dll!FModuleManager::LoadModule() (0x00007fff81602798) + 50 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\private\modules\modulemanager.cpp:238]
UE4Editor-HotReload.dll!FHotReloadModule::DoHotReloadInternal() (0x00007fff747949f8) + 44 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\developer\hotreload\private\hotreload.cpp:654]
UE4Editor-HotReload.dll!FHotReloadModule::DoHotReloadFromIDE() (0x00007fff7479455c) + 184 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\developer\hotreload\private\hotreload.cpp:1059]
UE4Editor-HotReload.dll!FHotReloadModule::Tick() (0x00007fff747a2b20) + 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\developer\hotreload\private\hotreload.cpp:995]
UE4Editor.exe!FTicker::Tick() (0x00007ff724ff13ea) + 32 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\public\containers\ticker.h:90]
UE4Editor.exe!FEngineLoop::Tick() (0x00007ff724ff0ae4) + 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\launchengineloop.cpp:2352]
UE4Editor.exe!GuardedMain() (0x00007ff724fe267c) + 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor.exe!GuardedMainWrapper() (0x00007ff724fe26ea) + 5 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor.exe!WinMain() (0x00007ff724ff2219) + 17 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor.exe!__tmainCRTStartup() (0x00007ff724ff3159) + 21 bytes [f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:618]
KERNEL32.DLL!UnknownFunction (0x00007fffa6f216ad) + 0 bytes [UnknownFile:0]
ntdll.dll!UnknownFunction (0x00007fffa92eeb64) + 0 bytes [UnknownFile:0]
ntdll.dll!UnknownFunction (0x00007fffa92eeb64) + 0 bytes [UnknownFile:0]

I have tried a similar thing on a newly created project and it Hot compiled without problems.

2

Hey Siveon,

I’m investigating this crash. Unfortunately we can’t know for sure what’s causing this crash until we get more details or steps to reproduce this crash. One option would be for you to duplicate your project and remove code from it until the crashing stops - then you’d know that the last code segment you removed was related to the crash. If you could give us a project stripped down to just the code that causes the crash, it would be immensely helpful in finding the cause.

As a secondary note, please try this on today’s 4.7.1 build to see if the crash is still occurring.

3

I’ve spent my time since then importing each file and asset manual to a newly created 4.7 project, so I no longer have this issue. However at some point I thought I had tracked the problem to a TArray, but then it would sometime compile without this array commented.