Unreal Engine Issues
Unreal Engine Issues
[CrashReport] Assertion on Mac: Could not create a libwebsocket - FNetworkFileServerHttp::Init()
UE - Platform - Mobile - Jun 22, 2017This 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 ...
Changing blueprint default values inside arrays only updates loaded child blueprints
UE - CoreTech - Jul 30, 2020The rules for delta serialization in UE4 are complicated, and the editor tries to hide them from you, which works 90% of the time but can lead to confusion and data loss in other situations. In the ...
Users project crashes when opening level that loads multiple sub-levels
UE - Foundation - Core - UObject - May 31, 2017Users project crashes when opening level that loads multiple sub-levels. Unable to reproduce this in a clean project so the users project is provided though Epic's box account (link is in the repro ...
Cannot select child anim BPs for use in linked anim layers
UE - Anim - Runtime - Jul 15, 2021From UDN: [Link Removed] Unable to set a Child ABP with inherited interface to a Linked Animation Layer Instance Class. I have a ABP_Biped which is our main ABP. I have the locomotion (idle+straf ...
Instanced Static Meshes ignore max World Position Offset Displacement for bounds after UpdateInstanceTransform is called
UE - Graphics Features - Jun 18, 2025When an Instanced Static Mesh Component (ISMC) uses a material with a non-zero Max World Position Offset Displacement, the bounds are correctly expanded at initialization. However, after calling Upd ...
Render target size mistmatch in ShaderDrawDebug
UE - Graphics Features - Jun 9, 2020We found a d3d debug validation assert in RDG_EVENT_NAME("ShaderDrawDebug"), with the full DLSS integration. It however also reproduces in (4.25.1-release, dev-rendering and the plugin branch with ...
[CrashReport] UE4Editor-Engine.dylib!bool FHighResScreenshotConfig::SaveImage<FLinearColor>()
UE - Graphics Features - Jul 27, 2017This is a common crash occurring on Mac in 4.15 and 4.16. Users have not provided any additional descriptions. Callstack from LogAssertion failed: Assertion failed: Bitmap.Num() == x * y [File:/Use ...
Wrong density calculation in UBodySetup::CalculateMass
UE - Simulation - Core - Sep 29, 2025Wrong density calculation in UBodySetup::CalculateMass. The licensee has provided the following analysis and suggested fix: In UBodySetup::CalculateMass, the following code is present: // physical ...
[CrashReport] UE4Editor_CoreUObject!FMemoryWriter::Serialize() [memorywriter.h:42]
UE - Foundation - Core - Jul 24, 2017This is a common cook crash affecting users in 4.16. It is possibly the same issue as described in [Link Removed] for past engine versions. Source Context 33 virtual void Serialize(void* ...
[CrashReport] Crash on Mac during Editor load (out of memory loading Boot.ddc): Assertion failed: A.ArrayNum >= 0
UE - Foundation - Core - Jun 14, 2017This is a common crash occurring for Mac users in the 4.16 release. It appears to occur during editor startup. The below details are taken from user log files.LogFileManager:Error: Requested read of ...