Editor can crash while performing a Hot Reload after a custom UClass class is added to the project

UE - Foundation - Cpp Tools - Hot Reload - Mar 14, 2019

Performing a Hot Reload after creating a custom UClass class can result in a crash. This was reported on Linux, but reproduced on Windows. Additional testing will be done on Linux to confirm the is ...

Using ConstructorHelpers::FClassFinder in a GameMode constructor may result in a default value or crash if the level is reloaded multiple times.

UE - Gameplay - Oct 27, 2015

Randomly selecting a character class from the GameMode constructor using ConstructorHelpers::FClassFinder can result in default or null character being set when the level is reloaded. It appears tha ...

FStateTreeExecutionContext::GetDebugInfoString() outputs wrong info and crashes when using linked state trees

UE - AI - Debugging - Apr 17, 2025

When using State Trees, the AI Debugger can be accessed during play to show information about their current execution state. If a behavior tree is currently in a state that references a linked tree, ...

Packaging failed with disabled plugin

UE - Foundation - Cpp Tools - Oct 9, 2018

Disabling any plugin causes packaging failure. No repro in 4.19 Also occurring when Disabling all platforms except for windows and changing configuration from development to shipping. ...

"Active" marker on shot track scales improperly when using Time Scale

UE - Anim - Sequencer - Apr 21, 2017

"Active" marker on shot track scales improperly when using Time Scale ...

Server crashes when client connects after Server has reloaded a sublevel with a deleted actor

UE - Networking - Jul 13, 2017

UNetDriver::DestroyedStartupOrDormantActors maintains a list of deleted startup (and dormant) actors. This is used to notify clients that have joined the server of Actors that need to be destroyed ...

Out-of-Bounds Access During Partial Updates of ISMC Per-Instance Custom Data

UE - Graphics Features - Jan 6, 2026

When using instance custom data values, removing an instance and changing the number of custom data floats in sequence can cause an array-out-of-bounds crash. The underlying arrays are not resized ...

Client crash on seamless travel in DataReplication with lag

UE - Networking - Jan 11, 2016

When server traveling, client may crash due to lag while attempting to replicate object/property. ...

Assertion failed: PlatformNeedsExtraDeletionLatency()

UE - Rendering - Architecture - RHI - Mar 5, 2019

Animating a HISM along a spline when many other HISMs are present will result in a crash in 4.22. Confirmed in 4.23 MAIN @ CL 5291468 ...

Making changes to a Camera Shake while previewing the Camera Shake triggers a crash

UE - Anim - Sequencer - May 23, 2022

This is not a regression. Tested in //UE4/Release-4.27 CL 18319896  Making changes to a Camera Shake while previewing the Camera Shake triggers an Assertion upon compiling. ...