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Bug: Composite Decorator Crash


I have a BehaviorTree and a Blackboard. I create a composite decorator, add a Blackboard decorator to it and the following things happen:

  • By default, the title of the BB decorator shows my first BB entry (bSomeBool Is Set). When I change it to what I need it to be, the title does not update.

  • When I try to duplicate that same decorator the engine crashes with the following crash log:

    UE4Editor_AIGraph!FAIGraphEditor::PasteNodesHere() [d:\projects\visual studio\ue482\engine\source\editor\aigraph\private\aigrapheditor.cpp:313] UE4Editor_AIGraph!FAIGraphEditor::PasteNodes() [d:\projects\visual studio\ue482\engine\source\editor\aigraph\private\aigrapheditor.cpp:298] UE4Editor_AIGraph!TBaseRawMethodDelegateInstance<0,FAIGraphEditor,void __cdecl(void)>::ExecuteIfSafe() [d:\projects\visual studio\ue482\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:582] UE4Editor_Slate!FUICommandList::ConditionalProcessCommandBindings() [d:\projects\visual studio\ue482\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:194] UE4Editor_Slate!FUICommandList::ProcessCommandBindings() [d:\projects\visual studio\ue482\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:138] UE4Editor_GraphEditor!SGraphEditorImpl::OnKeyDown() [d:\projects\visual studio\ue482\engine\source\editor\grapheditor\private\sgrapheditorimpl.cpp:66] UE4Editor_Slate!::operator()() [d:\projects\visual studio\ue482\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:3750] UE4Editor_Slate!FEventRouter::Route() [d:\projects\visualstudio\ue482\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:212] UE4Editor_Slate!FEventRouter::RouteAlongFocusPath,FKeyEvent>() [d:\projects\visual studio\ue482\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:194] UE4Editor_Slate!FSlateApplication::ProcessKeyDownEvent() [d:\projects\visual studio\ue482\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:3751] UE4Editor_Slate!FSlateApplication::OnKeyDown() [d:\projects\visual studio\ue482\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:3675] UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\projects\visual studio\ue482\engine\source\runtime\core\private\windows\windowsapplication.cpp:1259] UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\projects\visual studio\ue482\engine\source\runtime\core\private\windows\windowsapplication.cpp:1708] UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\projects\visual studio\ue482\engine\source\runtime\core\private\windows\windowsapplication.cpp:706] UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\projects\visual studio\ue482\engine\source\runtime\core\private\windows\windowsapplication.cpp:628] UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\projects\visual studio\ue482\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:792] UE4Editor!FEngineLoop::Tick() [d:\projects\visual studio\ue482\engine\source\runtime\launch\private\launchengineloop.cpp:2323] UE4Editor!GuardedMain() [d:\projects\visual studio\ue482\engine\source\runtime\launch\private\launch.cpp:142] UE4Editor!GuardedMainWrapper() [d:\projects\visual studio\ue482\engine\source\runtime\launch\private\windows\launchwindows.cpp:126] UE4Editor!WinMain() [d:\projects\visual studio\ue482\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]

Product Version: UE 4.8
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asked Jul 15 '15 at 11:59 AM in Bug Reports

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avatar image MieszkoZ STAFF Jul 15 '15 at 12:56 PM

Is this crash consistent and it happens after restarting the editor? Can you prepare a repro-project exhibiting this bug? I'm asking because this simply works so it's specific to something you do.



avatar image DamirH Jul 15 '15 at 01:53 PM


Yea I can reproduce it in 2 different projects. I just migrated my BehaviorTree. It's in Characters/NPCs/Enemies/AI. Check out the composite decorator on the left hand side of the tree. Open it up, add a Blackboard decorator, change some of the values and hit Ctrl+W on it. Crashes like clockwork for me.


avatar image Rudy Q ♦♦ STAFF Jul 15 '15 at 08:39 PM

Hello DamirH,

I was unable to reproduce this issue on our end. There were too many compile errors in the project that was sent. I have a few questions that will help narrow down what issue it is that you are experiencing.

Quick questions:

  1. Can you reproduce this issue in a clean project (no previous assets)?

  2. If so, could you provide a detailed list of steps to reproduce this issue on our end?

  3. Was this project upgraded from a previous version of the engine?

avatar image DamirH Jul 15 '15 at 08:49 PM

Hey there,

Sorry to hear about the compile errors, I migrated the assets to a clean project and I was able to open it... let me open up a clean project and I'll get back to you within 5 minutes.

avatar image DamirH Jul 15 '15 at 09:15 PM

Hello Rudy,

I have cleaned up all the files and I am opening up the project with the stock 4.8.1 version - the crash still happens. Here are my repro steps:

  1. Open up the behavior tree in Characters/NPCs/Enemies/AI

  2. Open up the composite decorator

  3. Add a Blackboard decorator to the graph. It will be set to MeleeEnemies Equal To 0 by default I believe

  4. Change the variable from MeleeEnemies to CowardiceLevel

  5. With the node selected, press Ctrl+W

The engine should immediately lock up.

Best regards, Damir H.

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Hello DamirH,

I was able to reproduce this issue on our end. I have written up a report ( UE-18740) and I have submitted it to the developers for further consideration. I will provide updates with any pertinent information as it becomes available. Thank you for you time and information.

Make it a great day

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answered Jul 16 '15 at 04:05 PM

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Rudy Q ♦♦ STAFF
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avatar image KeirBlackDelta Nov 23 '15 at 03:16 AM

This is still happening in 4.10. Any plans for a fix?

It's as easy to reproduce as:

  • create new blank project

  • create new behaviour tree

  • add new composite decorator

  • add a node inside this decorator

  • attempt to duplicate the node (ctrl+w)

  • crash

avatar image Rudy Q ♦♦ STAFF Nov 23 '15 at 01:47 PM

Hello KeirBlackDelta,

I went ahead and double checked on this issue for you. This issue has been resolved internally and the solution will be available in a later release of the engine. Thank you for your time.

Make it a great day

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