Assertion failed in FAudioDevice::UnregisterSoundClass when GC

UE - Audio - Aug 13, 2018

The licensee reported that check(IsInAudioThread()) was failed in FAudioDevice::UnregisterSoundClass when GC. The following is the call stack: 1 #00 pc 030d7b58 libUE4.so HandleError (/home/pirates ...

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, 2025

This 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 ...

Custom Event with array param does not take a pointer to the array

UE - Gameplay - Blueprint - Oct 12, 2016

When an array is passed into a BP custom event, the array's data is passed to the event rather than a pointer to the array itself. This means edits made directly from the event node's input pin (su ...

Editor Crashes when attempting to copy/paste nodes in Material Editor

UE - Graphics Features - Nov 18, 2014

UPDATE: 1/8/2015 Crash Reporter: [Link Removed] Callstack: <unknown module>! KERNELBASE!RaiseException() <unknown module>! UE4Editor_Core!FOutputDeviceWindowsError::Serialize() <unknown module> ...

Slate Widget fails to compile once added to a new project

UE - Foundation - Core - Jan 28, 2015

Slate Widget fails to compile when you add it to a new project. Expected as a user that anything in that default list should be able to be added and compile fine without making any changes. Compil ...

Compiling a Blueprint that uses a Select node with two different variations of Actor will crash the Editor in 4.9

UE - Gameplay - Blueprint - Jul 17, 2015

Compiling a Blueprint that uses a Select node with two different variations of Actor will crash the Editor in 4.9. In 4.8.2 binary, one input of a Select node will be disconnected on restarting the ...

Level Instance Property Override: Actor::Tags overridden pre-CS but clobbered by RerunConstructionScripts with no post-CS re-apply

UE - World Creation - Worldbuilding Tools - May 4, 2026

Summary When using the Level Instance Property Override system, overrides applied to `AActor::Tags` are silently lost for Blueprint actors whose Construction Script assigns or appends to `Tags`. The ...

Shader compiler errors when using enclosed local variables in a material while ray tracing is enabled

UE - Rendering - Architecture - RHI - Jan 23, 2020

A licensee is seeing an issue with a couple of post process materials after enabling ray tracing. While the materials presenting the issue fail to compile for different reasons, they both refernce t ...

iOS Launch On does not copy content to iOS/TVOS 13 devices

UE - Platform - Mobile - Aug 12, 2019

DeploymentServer fails to transfer the files LogPlayLevel: ********** DEPLOY COMMAND STARTED ********** LogPlayLevel: Running: F:\UE4-Release-4.23\Engine\Binaries\DotNET\IOS\DeploymentServer.exe ...

Editor crashes if user attempts to open a data table that only has one data type after closing and reopening editor

Tools - Jan 30, 2015

Editor crashes if user attempts to open a data table that only has one data type after closing and reopening editor Frequency: 2/2 Crash Reporter: Not currently available ...