Unreal Engine Issues
Unreal Engine Issues
UAbilityTask_SpawnActor::BeginSpawningActor may return true when SpawnedActor contains stale value
UE - Foundation - Mar 15, 2026UAbilityTask_SpawnActor::BeginSpawningActor assumes the incoming AActor*& SpawnedActor parameter is nullptr if no actor was spawned, but it does not initialize the parameter at the start of the func ...
Static light contained in a blueprint will need lighting rebuilt each time the project is reopened
UE - Gameplay - Jun 29, 2017Static light contained in a blueprint will need lighting rebuilt each time the project is reopened. This only seems to occur for a static light that is parented to a static mesh and then that static ...
Unreal Editor 5.4.4 crash when reproducing a LevelSequence in loop while PIE.
UE - Anim - Sequencer - Sep 9, 2024A crash inside Unreal Engine Editor version 5.4.4 occurs when reproducing a Level Sequence while in PIE. This issue is a regression. It only crashes in version 5.4.4. It was working correctly in ver ...
[CrashReport] Assertion failed: !PinRef->bWasTrashed | UEdGraphPin::SerializePin()
UE - Gameplay - Blueprint - Aug 29, 2017This is a common and longstanding crash that has occurred since at least 4.15 and affected nearly 500 users. The CrashGroup was previously linked to [Link Removed], but that had specific repro step ...
Second UVs wiped when using Merge Actors Tool
UE - World Creation - Worldbuilding Tools - HLOD - Jan 26, 2017The merge actor tool no longer saves additional UVs used for the merged mesh. This was not the case in 4.13, but in 4.14 and later this information is no longer present. Also worth noting is that i ...
Control Rig: crashes when compiling after rearranging input pins in an array in Example Rig Unit
OLD - Anim - Aug 20, 2019The crash doesn't occur every time, but it will happen within 3 swap and compiles in my experience. I got multiple different callstacks when I cause the crash using the reproduction steps (they are ...
Failed to generate Nanite data for mesh with bDoFastBuild enabled
UE - Graphics Features - Nanite - Oct 1, 2025If "bDoFastBuild" is enabled on a Static Mesh asset, in-editor it will never be able to have Nanite data built for it, preventing the Static Mesh from using Nanite. There is no way to fix this issu ...
Packaging Error When Setting Recast Nav Mesh Runtime Generation
UE - AI - Jan 25, 2016Setting the Runtime Generation on the Recast Nav Mesh to a different preset than what is set in the Project Settings causes an error to appear upon trying to package the project, and causes the pack ...
Project Crashes on Open when Implementing An Interface and Its Duplicate
UE - Gameplay - Blueprint - Apr 25, 2016The linked project crashes on open after attempting to implement an interface and a duplicate of that same interface with different function names. This has not been reproduced in a clean project, h ...
Editor ensure in USceneComponent::OnComponentDestroyed during Blueprint compilation GC
UE - Framework - Components - Jan 15, 2026An editor-only ensure can trigger during BP compilation when garbage collection cleans up transient components created as part of component replacement. During recompilation, old component instances ...