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UMG crashes Android


I'm getting a crash on Android when using UMG to move widgets.

I multiple animations that I try and play, and each one crashes the mobile when they start to play. If I remove everything from the animation (so it basically tries to play an empty animation) then everything works ok.

This is the call stack. Any ideas how to fix this?

 D/UE4: Assertion failed: Pair != nullptr [File:Runtime/Core/Public/Containers/Map.h] [Line: 444] 
 D/UE4: libUE4.so!FDebug::LogAssertFailedMessage(char const*, char const*, int, wchar_t const*, ...) 
 D/UE4: libUE4.so!FMovieSceneRootEvaluationTemplateInstance::CallSetupTearDown(IMovieScenePlayer&, FDelayedPreAnimatedStateRestore*) 
 D/UE4: libUE4.so!FMovieSceneRootEvaluationTemplateInstance::Evaluate(FMovieSceneContext, IMovieScenePlayer&, FMovieSceneSequenceID) 
 D/UE4: libUE4.so!UUMGSequencePlayer::PlayInternal(double, double, double, double, int, EUMGSequencePlayMode::Type, float) 
 D/UE4: libUE4.so!UUserWidget::PlayAnimation(UWidgetAnimation*, float, int, EUMGSequencePlayMode::Type, float) 
 D/UE4: libUE4.so!UBP_MainMenu_C__pf2028121400::bpf__ExecuteUbergraph_BP_MainMenu__pf_5(int) 
 D/UE4: libUE4.so!UUserWidget::execOnAnimationFinished(FFrame&, void*) 
 D/UE4: libUE4.so!UFunction::Invoke(UObject*, FFrame&, void*) 
 D/UE4: libUE4.so!UObject::ProcessEvent(UFunction*, void*) 
 D/UE4: libUE4.so!UUserWidget::OnAnimationFinished(UWidgetAnimation const*) 
 D/UE4: libUE4.so!UUserWidget::OnAnimationFinishedPlaying(UUMGSequencePlayer&) 
 D/UE4: libUE4.so!TBaseUObjectMethodDelegateInstance<false, UUserWidget, void (UUMGSequencePlayer&)>::ExecuteIfSafe(UUMGSequencePlayer&) const 
 D/UE4: libUE4.so!TBaseMulticastDelegate<void, UUMGSequencePlayer&>::Broadcast(UUMGSequencePlayer&) const 
 D/UE4: libUE4.so!UUMGSequencePlayer::Tick(float) 
 D/UE4: libUE4.so!UUserWidget::TickActionsAndAnimation(FGeometry const&, float) 
 D/UE4: libUE4.so!UUserWidget::NativeTick(FGeometry const&, float) 
 D/UE4: libUE4.so!SObjectWidget::Tick(FGeometry const&, double, float) 

Cheers, Chris

Product Version: UE 4.17
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asked Aug 27 '17 at 03:06 PM in Bug Reports

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avatar image Hyunwoo Kang Aug 29 '17 at 05:53 AM

I have same problem. :(
build ver: UE4.17.1 build setting: Blueprint Nativization Method: Inclusive error point: Play UMG Animation in construct event.

avatar image Piranhi Aug 29 '17 at 09:57 AM

Glad it's not just me.

I've tried everything I can think of to fix the issue. I don't think this happened with 4.17, but it definitely does with 4.17.1.

avatar image Piranhi Aug 31 '17 at 07:26 AM

Hey - Any update from Epic Staff? This is stopping me from publishing my game :(

Cheers, Chris

avatar image Piranhi Sep 08 '17 at 08:23 AM

Hey - It's been over 3 weeks and still no reply :( This is the only bug preventing me from publishing. Any reply would be really appreciated

avatar image Thomas G ♦♦ STAFF Sep 11 '17 at 05:35 PM

Hello Piranhi,

I was unable to reproduce the issue you are experiencing on our end. I have a couple of questions about your issue to help me investigate further.

  1. Can you reproduce this issue in a new project?

  2. If so could you provide a detailed list of steps, so that I can reproduce this issue?

  3. How many elements are you controlling through each animation?

  4. How are you calling the animation to play? Through the widget, or through another blueprint?


avatar image Piranhi Sep 21 '17 at 08:30 PM

Hey Thomas,

4.18 seems to have fixed the issue. It's added a few weird UMG bugs, but at least the game runs now.

Just to quickly answer some of your questions:

How many elements are you controlling through each animation? - Between 1 and 10

How are you calling the animation to play? Through the widget, or through another blueprint? - Through blueprints in the widget.

Cheers, Chris

avatar image Thomas G ♦♦ STAFF Sep 27 '17 at 06:02 PM

Hello again Chris,

I am still unable to reproduce the issue you are experiencing. Were you able to reproduce the crash in a new project?

avatar image 7ortis7 Sep 02 '17 at 02:23 PM

Same problem here

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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 follow up.


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answered Oct 05 '17 at 01:58 PM

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Thomas G ♦♦ STAFF
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