Map placed actor binding to another actor's Event Dispatcher (multicast delegate) results in duplicate bindings after blueprint recompile

UE - Framework - Blueprint - Apr 17, 2025

Context Blueprint actors placed on the map can bind to another actor's event. If an ActorB has a reference to ActorA, it can bind to an event dispatcher in A by creating an event node in ActorB's e ...

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 ...

Crash when changing a Play Node's "Sequence" to a Montage

OLD - Anim - Jan 20, 2016

I understand that this is not something you're intended to be able to do (Montages aren't used this way), but we should bar the user from inserting a montage into this variable slot. Crash occurs w ...

[CrashReport] Mac crash - FMetalRenderPass::AsyncCopyFromBufferToTexture()

UE - Graphics Features - Sep 14, 2017

This is an infrequent Mac crash that has occurred for a few users since 4.16. Users have not provided any description of their action when the crash occurred. Callstack from Log[2017.08.26-18.54.51 ...

Compile error during build stage when packaging for tvOS

UE - Platform - Mobile - Dec 9, 2016

Compile error packaging for tvOS: Does not affect iOSUATHelper: Packaging (tvOS): UnrealBuildTool: D:\Build\joseph.wysosky_Main\Engine\Source\Runtime\Core\Private\iOS\IOSAppDelegate.cpp(388,12): ...

[CrashReport] Assertion failed on Linux: SharedContext.hGLContext in OpenGLLinux.cpp

UE - Platform - Linux - Jun 16, 2017

This is a top community crash occurring on Linux. The two linked CrashGroups have nearly identical callstacks. A log file is attached. Additional information is currently unavailable. Callstack f ...

[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 ...

[CrashReport] UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::print_constant()

UE - Graphics Features - Sep 22, 2017

This is an early trending crash coming out of the 4.18 previews. It occurs on Mac, and all affected project names indicate it is related to AR. Users have not provided any descriptions of their ac ...

[CrashReport] UE4Editor-MetalRHI.dylib!FMetalRenderPipelineDesc::CreatePipelineStateForBoundShaderState()

UE - Graphics Features - Jun 29, 2017

This is a common crash affecting Mac users in the 4.16 release. Mark.S: "one of the visualisation shaders is setting up bogus render state" Callstack from LogLogActorFactory: Actor Factory create ...

Navigation crashing on PIE in absence of NavOctree

UE - AI - Mar 17, 2015

Access violation - code c0000005 (first/second chance not available) UE4Editor_Engine!UNavMeshRenderingComponent::GatherData() + 18874 bytes [e:\downloads\unrealengine-4.7\unrealengine-4.7\engine\s ...