Crash when element is added to a map variable with unhashable key

UE - Gameplay - Mar 21, 2017

Crash when element is added to a map variable with unhashable key. An error is thrown on compile but an element can still be added under the Details panel of the variable. Crash Reporter: [Link Rem ...

Bug - Animations and Keep State Fail when scrubbing backward.

UE - Anim - Sequencer - Jan 30, 2020

If you scrub past an animation with keep state, and scrub into an animation with defaults everything is fine. When you scrub back to the animation with keep state, the animation breaks, until there ...

Color space transform in the UI composition is incorrect on DX12 HDR (r.HDR.UI.CompositeMode=1)

UE - Graphics Features - Jun 11, 2021

Color space conversion in the UI composition is incorrect on DX12 HDR. In the main() function In CompositeUIPixelShader.usf, you can see the following color space transform.// sRGB -> RRT -> ODT ...

Material slot assignment incorrect after mesh reduction completely removes all triangles from a section

When mesh reduction results in a section becoming empty, the material slots are incorrectly assigned. e.g. if section 0 gets removed due to it having no triangles after reduction, then its material ...

Editor-only blueprints like WidgetBlueprint are not added to cooked asset registry class hierarchy

UE - Core - Systems - Aug 10, 2022

Both the Asset Registry and Asset Manager look for all subclasses of UBlueprintCore and use that to search for blueprint classes and construct an inheritance hierarchy. This always works in editor b ...

Deferring Blueprint CDO construction at load time is leading to some data loss.

UE - Gameplay - Blueprint - Jan 27, 2023

Various licensees are reporting data loss on load due to the change that was made for [Link Removed] in which we now defer Blueprint CDO construction on load until the finalization phase. This issu ...

TMap does not rehash when the property change if the key is struct

UE - Editor - Verse Class Editor - Feb 17, 2023

If TMap's Key is a unique Struct, TMap's rehash will not run even if elements are added or changed in DetailPanel such as DataAsset. So TMaps's Find etc. will fail This issue is very similar to ...

Sequencer: Camera Lock Breaks After Closing Sequencer and Re-entering PIE

zComponent - Archive - Oct 9, 2025

Viewport camera lock in Sequencer fails to persist correctly after running PIE with Sequencer open, then closing Sequencer and running PIE again. The issue consistently reproduces using the attached ...

Crash on Mac when adding Convex Collision to a mesh converted from a brush

UE - Platform - Apple - Jun 6, 2017

This is one of the top Mac crashes occurring in 4.16. Caused by adding Auto Convex Collision to a mesh converted from a brush. Does not occur on Windows. User DescriptionsI was trying to add a conv ...

UKismetArrayLibrary::GenericArray_Shuffle is weighted to return some results more than others

UE - Gameplay - Aug 15, 2017

The implementation of UKismetArrayLibrary::GenericArray_Shuffle() will generate certain array shuffle results more often (up to three times as much) than others, rather than having a roughly equal c ...