Unreal Engine Issues
Unreal Engine Issues
FMultiReaderSingleWriterGT isn't thread safe
UE - Foundation - Core - May 17, 2016From https://udn.unrealengine.com/questions/292741/fmultireadersinglewritergt-isnt-thread-safe.html: I've found that FMultiReaderSingleWriterGT has at least 2 bugs: The one that caused a deadlock ...
[CrashReport] Commandlet crash - UE4Editor_Engine!FAnimationUtils::CompressAnimSequenceExplicit() [animationutils.cpp:621]
OLD - Anim - Sep 7, 2017This is an infrequent commandlet crash that has affected a number of users exclusively in 4.17.1 (possible regression from 4.17.0?). There are also two instances of older cases in 4.13 and 4.15, bu ...
Reversed Animations don't play properly using Skeletal Mesh Pose and animations with Keep State in Sequencer
UE - Anim - Sequencer - Nov 26, 2018The bug seems to only reproduce when setting animations in sequencer and only if the animations are set to "Keep state". Setting them to "restore default" makes the reversed animation play correctly ...
[CrashReport] UE4Editor_Engine!FAnimCurveBase::SetCurveTypeFlag() [animcurvetypes.cpp:18]
OLD - Anim - Jun 13, 2016This Jira was created from CrashReports submitted by the public due to the high number of occurrences. Descriptions from users are provided below. Error message: Access violation - code c0000005 ( ...
[CrashReport] UE4Editor_AlembicLibrary!AbcImporterUtilities::GenerateSmoothingGroupsIndices()
UE - Gameplay - Aug 5, 2016This JIRA is being entered as a result of it being one of the top crashes occurring in 4.13 Preview 1. Error message: Assertion failed: (Index >= 0) & (Index < ArrayNum) [Link Removed] [Line: 833] ...
Using a Macro to access a variable from another Actor causes a crash in Standalone
UE - Gameplay - Blueprint - Jun 8, 2015Using a Macro to access a variable from another Actor causes a crash in Standalone. This does not seem to affect any other preview in editor, nor packaged games. Reproduced in 4.7.6, 4.8 Preview 4, ...
Updates to DesiredFocusWidget for a UserWidget are not propagated to existing instances of it inside the WidgetTree of other widgets
UE - AI Workflows - UI Systems - Nov 17, 2025This issue has been reproduced in UE 5.3 to 5.7 and source versions. A repro project is available. Below are the findings from an initial investigation of the problem. Normally, when a UserWidget p ...
Crash when attempting to change the parent of a material instance constant through editor scripting
UE - Rendering - Architecture - Materials - Apr 9, 2025The built-in class "UMaterialEditingLibrary" provides various editor scripting functions related to creating and editing materials and material instances. One of these functions, UMaterialEditingLib ...
[CrashReport] UE4Editor_CoreUObject!FWeakObjectPtr::operator=() [weakobjectptr.cpp:28]
UE - Anim - Sequencer - Nov 3, 2016This Jira was created from CrashReports submitted by the public due to the high number of occurrences. Error message: Access violation - code c0000005 (first/second chance not available) Source C ...
Users can create project with name of "Stack" which causes conflict with existing "Stack.h"
Tools - Sep 12, 2016Users can create project with existing name of "Slack" which causes conflict with existing Slack.h. Call stack is log file. ...