UE4 Crashes if multiple Vive Trackers or Lighthouses are used

UE - Platform - XR - Jan 24, 2018

User reports that if more than 5 trackers are connected, UE4 crashes Suggested fix: Root cause of bug is related to the fact that UE has no setup to receive input events from Vive Trackers. (we ha ...

Available network bandwidth is too low for uncapped but slow frame rates

UE - Networking - Sep 24, 2020

The networking system has a max frame rate of 120hz by default. Inside UNetConnection::Tick it computes an estimated bandwidth by using that max frame rate, the engine's max frame rate, and the actu ...

UClass::SparseClassDataStruct null at editor-time for child blueprints until compile

UE - Framework - Blueprint - May 29, 2024

Child blueprints of a blueprint of a native actor class with sparse data can have an incorrectly null SparseClassDataStruct value, and thus fail to initialzie their SparseClassData. This affects edi ...

AimOffset and Blenspace graphs causing crash for some users

OLD - Anim - Mar 30, 2015

Users are experiencing crashes when using the AimOffset and Blendspace graphs. I am unable to reproduce this locally, but judging by the Bugg in crash reporter, this is not an isolated incident. [ ...

UAnimNotify::Notify not called during USkeletalMeshComponent interaction with UPhysicsControlComponent when PhysicsBlendWeight is zero

UE - Anim - Synthesis - Physics Control - Mar 30, 2025

UAnimNotify::Notify not called during USkeletalMeshComponent interaction with UPhysicsControlComponent when PhysicsBlendWeight is zero. The licensee has provided his analysis of the code: If USkelet ...

SpringArmComponent with "Use Camera Lag Substepping" does not handle fluctuating frame rates correctly

UE - Gameplay - Jun 4, 2024

The description of SpringArmComponent's "Use Camera Lag Substepping" option says "sub-step camera damping so that it handles fluctuating frame rates well". However, as noted and explained by a licen ...

[CrashReport] UE4Editor_ShaderCore!FVertexFactory::Set() [vertexfactory.cpp:190]

UE - Graphics Features - Nov 17, 2017

This is a common crash in the 4.18 release. It is the exact same callstack (and crashGroup) as in [Link Removed], although that Jira had specific repro steps and was confirmed fixed in 4.18.0. The ...

Launch on fails during staging with a SafeCopyFile Exception for MfMedia.uplugin

Tools - Jan 10, 2017

Was able to repro this on machines with and without machines set up for Xbone testing. ...

Users Unable to create C++ Projects

UE - Foundation - Core - Mar 6, 2015

2nd AH post with the same issue: https://answers.unrealengine.com/questions/183441/cant-load-c-projects.html Multiple people have reported not being able to create a C++ project. Creating a Bluepr ...

[CrashReport] Assertion on Mac: Could not create a libwebsocket - FNetworkFileServerHttp::Init()

UE - Platform - Mobile - Jun 22, 2017

This is a common crash on Mac that occurs in the 4.16 release. This appears similar to [Link Removed], which was closed with the 4.13 release. Users have not provided descriptions. Many (but not a ...