BP - Nativization will fail at cook time if a BP class and a User-Defined Structure reference each other.

UE - Gameplay - Blueprint - Apr 20, 2017

Note: This happens with "Exclusive" nativization mode as well. This occurs because the nativized UDS 'GetDefaultValue()' method is generated into a .h file rather than a .cpp file. This creates a c ...

Localization manifest writing fails if source control is hooked up and the manifest file does not exist already.

UE - Editor - UI Systems - Localization - Jun 16, 2015

First one happens on a clear project without any localization settings ever made. Gather Text commandlet log has theese lines in it: [2015.06.16-13.21.56:396][ 0]LogInit:Display: SourceControl:Err ...

Using xcode-select to switch between Xcode 10 and Xcode 11 beta can cause Xcode 11 to be unrecognized by the editor

UE - Platform - Apple - Jul 16, 2019

After switching from Xcode 11.0 Beta 3 (11M362v) to Xcode 10 (10A255) and then back to Xcode 11, the editor no longer recognized that Xcode was installed on my machine when trying to use Xcode 11 as ...

Assertion failed after closing project on Oculus Mobile - Referencing AudioMixerSourceManager.cpp:300

UE - Audio - Apr 30, 2019

This assertion seems to occur when closing the project while a sound is playing on the device. Assertion failed: CommandBuffers[NextIndex].SourceCommandQueue.Num() == 0 [File:D:/P4Workspaces/Switch ...

[CrashReport] Crash on Mac - UE4Editor-SlateCore.dylib!SWindow::IsVisible()

UE - Platform - Apple - Jun 23, 2017

This is a common crash on Mac in the 4.16 release, and has occurred with low frequency since at least 4.11. Users have not provided any descriptions, so additional information is currently unknown. ...

ApplicationReceivedScreenOrientationChangedNotificationDelegate does NOT work properly on Android

UE - Platform - Mobile - Aug 5, 2019

ApplicationReceivedScreenOrientationChangedNotificationDelegate supports iOS but not Android. Probably, Java_com_epicgames_ue4_GameActivity_nativeOnConfigurationChanged should be useful for fix thi ...

Morph target is not applied on the first frame in Level Sequence

UE - ACT Character - Control Rig - Dec 4, 2025

When a skeletal mesh with morph targets spawns in the sequence, the morph is not reflected in the first frame.  In the ProcessStage_SkinCache call of SkeletalMesh, MorphVertexBuffer->SectionIds is ...

ensure(false) being fired in FGenericParticlePairMidPhase::FindOrCreateConstraint from key collision

UE - Runtime - Simulation - Jan 27, 2025

ensure(false) being fired in FGenericParticlePairMidPhase::FindOrCreateConstraint from key collision. The licensee reports one of their users reported this issue and they were able to reproduce a fe ...

[CrashReport] UE4Editor_Renderer!FGlobalShader::SetParameters<FRHIPixelShader * __ptr64,FRHICommandList>() [globalshader.h:134]

UE - Graphics Features - Jun 29, 2016

This JIRA was created from crash reports submitted by users due to it being one of the top crashes occurring in 4.12.4 This might be a regression because the crash has only just started in 4.12.4. ...

TMap where key is an FString: initializer list will accept bad MakeTuple

UE - Core - Systems - Sep 2, 2026

POST LINK: https://forums.unrealengine.com/t/tmap-where-key-is-an-fstring-initializer-list-will-accept-bad-maketuple/2747443 POST BODY:Summary A TMap where the key is an FString can be created lik ...