Unreal Engine Issues
Unreal Engine Issues
Duplicating Level With Large _BuiltData File Results in Editor Crash
UE - Foundation - Core - Jun 7, 2018Trying to duplicate a level in the editor that has a large _BuiltData file results in a crash. In the case of the supplied test level, it is over 3 GB. Crash repros in 4.19.2 and Main (CL 4115885). ...
Cannot create Editor Toolbar Button with the name "Button"
Tools - Apr 19, 2017The plugin fails to be created with the name "Button". The name button or BUTTON works as a plugin name. If there are some names that plugins cannot be called, then an error/warning message in the o ...
The socketbuilders do not properly join multicast groups on iOS
UE - Networking - Jul 26, 2019On iOS, using the code in the UDP socketbuilders causes the sessions tool to not join with iOS devices. Giving the error EADDRNOTAVAIL. If the user falls back to the other code function that uses th ...
NormalizePackageNames() should interpret 'exclude developer folders' to also exclude packages in ExternalActors and ExternalObjects
UE - CoreTech - Oct 14, 2022In NormalizePackageNames() (PackageUtilities.cpp), there is a PackageFilter parameter, which can be set to exclude developer packages (NORMALIZE_ExcludeDeveloperPackages). The code only checks the b ...
Placing a section at the end of montage is not properly handled
UE - Anim - Gameplay - Feb 24, 2024Placing a section at the very end of a montage with no duration or animation assigned after it is not properly handled. Normally sections with 0 length are skipped and search continues since they ...
FAnimMontageInstance::SetNextPositionWithEvents can trigger all notifies on a montage/sequence
UE - Anim - Runtime - Jun 24, 2025This issue happens when Sequencer loops a dynamic montage. FAnimMontageInstance::ForcedNextFromPosition is set to 0 and ForcedNextToPosition is effectively the delta time. However, FMontageSubStep ...
Performance slowdown when ray tracing is disabled due to SetResidencyPriority
UE - Rendering Architecture - RHI - Jul 17, 2025When a game is compiled with ray tracing disabled (D3D12_RHI_RAYTRACING=0) and the GPU the game is running on becomes low on VRAM, frame time is negatively impacted and doesn't recover. The D3D12_RH ...
Crash when exporting Static Meshes as an FBX (UE4Editor-SlateCore.dll!SWidget::OnQueryShowFocus)
Tools - Sep 21, 2017Possibly related to [Link Removed] ...
Crash when removing cloth apb's assigned to asset
UE - Simulation - Physics - Character - Apr 27, 2016When removing already assigned cloth asset from a skeletal mesh it will crash the editor. I was able to reproduce this with the Owen asset from Content Examples, but was unable to get it to work fro ...
Crash on Device when Deploying Mobile Project with Modulated Shadows and Planar Reflections on iOS 9
UE - Platform - Mobile - Jan 6, 2017A crash occurs on iOS when deploying the licensee's project using iOS 9 version. The crash does not occur when deployed to a device using iOS 10 version. They believe the crash to be related to Pl ...