UMG Crash on open

Development Programming & Scripting
1

When I was using v 4.9 the Profiler in Session Frontend was always crashing. Now after updating to 4.10 it works but the Widget Editor crashes always even before window is shown. I tried creating empty widget and it crashed too.
To be exact I found that it crashes only on one project. One but the most important :frowning: I don’t want to lose > 5 months of development because of that :((

Error and crash dump:

Ensure condition failed: ObservedKeyNames.Num() > 0 [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.10\Engine\Source\Runtime\AIModule\Private\BehaviorTree\Decorators\BTDecorator_BlueprintBase.cpp] [Line: 66]

Stack: 
UE4Editor-Core.dll!FWindowsPlatformStackWalk::StackWalkAndDump() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\core\private\windows\windowsplatformstackwalk.cpp:175]
UE4Editor-Core.dll!FDebug::EnsureFailed() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\core\private\misc\outputdevice.cpp:276]
UE4Editor-Core.dll!FDebug::OptionallyLogFormattedEnsureMessageReturningFalse() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\core\private\misc\outputdevice.cpp:385]
UE4Editor-AIModule.dll!UBTDecorator_BlueprintBase::PostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\aimodule\private\behaviortree\decorators\btdecorator_blueprintbase.cpp:66]
UE4Editor-CoreUObject.dll!UObject::ConditionalPostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\obj.cpp:723]
UE4Editor-CoreUObject.dll!UObject::ConditionalPostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\obj.cpp:719]
UE4Editor-CoreUObject.dll!EndLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1286]
UE4Editor-CoreUObject.dll!LoadPackageInternal() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1042]
UE4Editor-UnrealEd.dll!UEditorEngine::Map_Load() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\editor\unrealed\private\editorserver.cpp:2367]
UE4Editor-UnrealEd.dll!UEditorEngine::HandleMapCommand() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\editor\unrealed\private\editorserver.cpp:5876]
UE4Editor-UnrealEd.dll!UEditorEngine::Exec() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\editor\unrealed\private\editorserver.cpp:5370]
UE4Editor-UnrealEd.dll!UUnrealEdEngine::Exec() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\editor\unrealed\private\unrealedsrv.cpp:743]
UE4Editor-UnrealEd.dll!FEditorFileUtils::LoadMap() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\editor\unrealed\private\filehelpers.cpp:2014]
UE4Editor-UnrealEd.dll!FEditorFileUtils::LoadDefaultMapAtStartup() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\editor\unrealed\private\filehelpers.cpp:3215]
UE4Editor-UnrealEd.dll!FUnrealEdMisc::OnInit() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\editor\unrealed\private\unrealedmisc.cpp:301]
UE4Editor-UnrealEd.dll!EditorInit() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\editor\unrealed\private\unrealed.cpp:86]
UE4Editor.exe!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\launch\private\launch.cpp:133]
UE4Editor.exe!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor.exe!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]
UE4Editor.exe!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32.dll
ntdll.dll
ntdll.dll
2

Hello RazzorFlame,

I have a few questions for you that will help narrow down what issue it is that you are experiencing.

quick questions:

  1. I saw that you said this is only happening in one of your projects, however can you reproduce this issue in a clean project?
  2. If so, could you provide a detailed list of steps to try and reproduce this issue on our end?
  3. Can you provide screen shots of any blueprints that may be involved with this issue?

Please note that we do not recommend active development in the preview builds of the engine. A preview build is considered unstable and is recommended for testing purposes only.

3

Hello RazzorFlame,

We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will offer further assistance.

Thank you.