Assertion failed: (Index >= 0) & (Index < ArrayNum) when importing large Alembic file

UE - Editor - Content Pipeline - Datasmith - Importer - May 3, 2022

Regression testing done on //UE4/Release-4.27.2 CL-18427296 and this issue did occur. [Link Removed] [Link Removed] Below is snips of customers description and proposed workaround:Importing alembi ...

StreamingGeneration: Actor desc mutator phase now writes ActorDescView directly, breaking the cluster-invariant check in ValidateContainerInstanceDescriptors

UE - Engine Scaling - Streaming - World Partition - May 22, 2026

This report is from an EPS case: We hit a regression upgrading our project from 5.7 to 5.8. Map Check (and any other path that ends up calling UWorldPartition::CheckForErrors) assert inside FWorld ...

Crash when trimming animation and then undoing action

UE - Runtime - Animation - May 30, 2023

Repro rate: 3/3 times This is a regression as the issue does not occur in 5.1.1  ...

[CrashReport] Linux crash - llvm::TargetLowering::LowerCallTo()

UE - Platform - Linux - Jul 20, 2017

This is a common Linux crash in 4.16.2. ...

Control Rig settings are not retained between editor sessions or carried into deployed game

UE - Anim - Rigging - Control Rig - Jun 10, 2020

Control Rig settings are not retained between editor sessions or carried into deployed game ...

Linux crashes in the Project Browser without using the -nocef command

UE - Platform - Linux - Feb 22, 2022

When opening Unreal Editor on Linux, the Project Browser opens but is completely unresponsive. Shortly afterwards the editor will crash. If you use the -nocef command when opening the Editor, everyt ...

Visible dithered quantization to remove banding in New Temporal AA Quality

UE - Graphics Features - Oct 6, 2015

Since changing the temporal history buffer to 11:11:10 from FP16, it looks as there is visible dithered quantization to remove banding when rendering. (Taken from conversation on Forum Post linked f ...

Attempting to build lighting in project crashes editor

UE - LD & Modeling - Terrain - Landscape - May 18, 2016

Attempting to build lighting in user's project crashes editor. Frequency: 3/3 CrashReporter: N/A ...

Crash when fast moving Character objects has Teleporting enabled

UE - Runtime - Simulation - Nov 28, 2022

Reproduced 3/3 times. Issue does not occur in //UE4/Release-4.27, so Confirmed Regression. ...

Blueprints not marked dirty when variables in referenced actors are renamed

UE - Gameplay - Blueprint Compiler - Feb 20, 2018

Blueprints using renamed variable do not indicate that they need to be recompiled. (However errors are shown on play) It is possible to not see an error if you add a variable with the same name as ...