Unfocused Standalone window has reduced performance

UE - Rendering - Architecture - RHI - Aug 25, 2020

User description: When I run two windowed standalone instances to test multiplayer, the unfocused window gets about 2-5 fps...but if I focus on it, smooth 120fps, yet the opposite screen is now onl ...

Incorrect behavior after attaching an actor to a non-root component of another actor in the Editor

UE - Editor - Workflow Systems - Jul 3, 2024

UE allows actors to be attached to other actors. More precisely, it allows the root component of an actor (child) to be attached to any component of another actor (parent). From now on, "parent" and ...

Crash Clicking on Enum in BT Decorators After the Enum Has Been Altered

UE - AI - Apr 5, 2017

Clicking on a Behavior Tree decorator that references an Enum blackboard key will crash the editor if that Enum has been altered in the method described in the repro steps. If you set decorators to ...

When using Perforce, saving a level over another leaves the target umap file as "marked for delete"

UE - Editor - Workflow Systems - Mar 11, 2025

When working on a level asset and using command "File – Save Current Level As..." to save it over a different level asset, the engine first deletes the target level (that's going to be overwritten) ...

[CrashReport] Assertion failed: TaskDataArray.Num() == Exporter->VolumetricLightmapTaskGuids.Num()

UE - Graphics Features - Lumen - Oct 2, 2017

This is a trending crash coming out of the 4.18 Previews. Users have not provided any descriptions of their actions when the crash occurred, but at least two of the affected projects are being creat ...

iOS Metal-based build crashes at launch with sub-levels.

Tools - May 16, 2016

Application crashes when deploying a game to iOS with Metal enabled. This has only been reproduced if a sub-level has been added to the starting level within the project. This seems to only happen ...

[CrashReport] UE4Editor_D3D11RHI!VerifyD3D11Result() [d3d11util.cpp:200]

UE - Editor - UI Systems - Slate - May 9, 2016

This Jira was created from CrashReports submitted by the public due to the high number of occurrences. Error message: Fatal error: [Link Removed] [Line: 200] SwapChain->ResizeBuffers(1,SizeX,SizeY ...

[CrashReport] UE4Editor_Renderer!FSceneRenderTargets::GetGBufferResourcesUniformBuffer() [scenerendertargets.h:408]

UE - Graphics Features - Jan 18, 2016

This Jira was created from CrashReports submitted by the public due to the high number of occurrences. Descriptions from users are provided below. Error message: Assertion failed: IsValidRef(GBuff ...

Crash after adding Virtual Bone, then Creating Asset

OLD - Anim - Jul 5, 2017

Occurs on? 4.16 - 3466753 - YES 4.17 - 3521650 - YES Error message: Assertion failed: RefBonePose.Num() == NumBones [Link Removed] [Line: 4400] Source Context:4387 ResetAnimation(); 4388 ...

Shipping build crash when unplugging then replugging Oculus HMD

UE - Platform - XR - Nov 9, 2016

Game crashes in shipping build when un-pluging the Oculus HMD, then plugging it back in. Confirmed in 4.13.2 from the launcher, did not repro via same steps in 4.14 preview 3 ...