Crash when a subsystem calls GetSubsystemArray() on its owner while engine code is iterating on subsystems also obtained through GetSubsystemArray()

UE - Gameplay - Aug 6, 2024

In some occasions, engine code iterates over a certain subsystem type by calling FSubsystemCollection::GetSubsystemArray() and then calling some method on all subsystems of the returned array. This ...

Backwards-compatibility broken for the CDOs of Python-generated Unreal Types because of missing redirectors

UE - Editor - Workflow Systems - Feb 11, 2025

Previously, all Unreal Types generated by python scripts would be created inside package "/Engine/PythonTypes". This was changed by [CL 32478991 in ue5-main branch], which meant to "remove the restr ...

iOS fails during build step with OSS Facebook plugin enabled due to spaces in filepath

UE - Platform - Mobile - Feb 8, 2019

When a user tries to package or launch onto an iOS device they will fail at the build step due to:[3/8] sh Unzipping: /Users/Shared/Epic Games/UE_4.22/Engine/Source/ThirdParty/Facebook/IOS/FacebookS ...

"FVector contains NaN" on packaged builds for Debug configuration

UE - Graphics Features - Lumen - May 6, 2022

Customer Provided Description:This was experienced in UE 5.01 - custom installed engine (No changes to UE code, simply added the Debug build configuration, see the following command): "c:%ue_dire ...

Crash handling: Prevent reports of assertions during shutdown after an assertion

UE - CoreTech - Aug 8, 2024

CriticalErrors in FWindowsErrorOutputDevice::Serialize (and other platforms) run some code after the error is detected rather than immediately terminating the process. Some of this other code is spe ...

[CrashReport] UE4Editor_MovieSceneTools!FPropertySection::GetPropertyValue<float>() [propertysection.h:70]

UE - Anim - Sequencer - Sep 20, 2017

This is a somewhat common crash in 4.17. Users have not provided any descriptions of their actions when the crash occurred. Source Context 58 /** Gets the current value of the property w ...

Actors disappearing after saving a large number of modifications to world partition maps

UE - Editor - Workflow Systems - Nov 4, 2022

From Licensee: "We've encountered a world partition bug where newly created actors go missing in the viewport and Outliner after saving modifications to a large number of actors. This bug is partic ...

Foliage is placed on LevelInstanceActor does not follow basecomponent when the LevelInstanceActor moves

UE - World Creation - Worldbuilding Tools - Foliage - Jun 24, 2022

Foliage usually follows when the Transform of the placed ground or floor changes. However, if the ground or floor is a Level Instance Actor, it will not follow. The cause is in the code below. voi ...

[CrashReport] UE4Editor_CoreUObject!UObject::CreateDefaultSubobject() [obj.cpp:118]

UE - Foundation - Core - UObject - Apr 4, 2017

Was created from CrashReports submitted by the public due to the high number of occurrences. Descriptions from users are provided below. Error message: Fatal error: [Link Removed] [Line: 117] No o ...

Actor Class Reference can take invalid Value, can lead to crash

UE - Gameplay - Blueprint - Oct 4, 2017

REGRESSION: Can be certain as this testing was blocked by [Link Removed] Through a specific chain of events (see repro), it's possible to have a non-actor as the value for an Actor Class Reference, ...