Using dynamic bindings in a code class will result in the bindings becoming a permanent part of any Blueprint created from that class if a hot reload is performed.

UE - Foundation - Core - Mar 26, 2015

If dynamic bindings are being used in a custom code class from which Blueprints are derived, any hot reload will make the bindings a permanent part of the Blueprint and they cannot be removed or cha ...

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 ...

Lighting channels are not supported with tiled lighting

UE - Graphics Features - Aug 15, 2016

Reported via UDN ...

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 ...

Sequential Level Loading in Python causes Crash

UE - Editor - Workflow Systems - Apr 16, 2019

Loading all the levels selected in the Content Browser and running the aforementioned Python script causes the editor to crash Tested in 4.20.3 (CL - 4369336), 4.21.2 (CL - 4753647), 4.22 (CL - 5 ...

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. ...

Virtual Bone caused nanite skinned mesh crash

UE - Graphics Features - Nanite - May 31, 2025

When a Nanite skeletal mesh has a virtual bone the engine can crash when changing LODs ...

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 ...