Sub-world partitions do not properly handle partial editor loading as world partition standalone level instances' spatially loaded actors do not get loaded even when the Level Instance is force loaded or loaded in by region.

UE - World Creation - Worldbuilding Tools - World Partition - Aug 19, 2025

Context Level Instancing is a level-based workflow designed to improve and streamline the level editing experience. In a standalone Level Behavior, when the Level Instance Actor is loaded through it ...

World Partition - Deleted actors can become unloaded prior to saving

UE - World Creation - Worldbuilding Tools - World Partition - Apr 11, 2025

In world partition levels, deleted actors can become unexpectedly unloaded prior to saving, causing loss of work. Specifically, this issue occurs after the undo history has been cleared (either manu ...

[CrashReport] <unknown module>!UE4Editor_Core!FDebug::AssertFailed()

UE - Foundation - Core - Mar 28, 2016

Error message: Assertion failed: (Index >= 0) & (Index < ArrayNum) [Link Removed] [Line: 678] Array index out of bounds: 0 from an array of size 0 Source Context: 80 } 81 else ...

Editor Crashes when placing a widget blueprint from one widget blueprint into another via the user created section

UE - Editor - UI Systems - Oct 8, 2014

CHANGELIST: 4.5.0-2316912 CRASHREPORT: Did not produce an error report CALLSTACK: Did not produce an error report DESCRIPTION:   Editor Crashes when placing a widget blueprint from one widget b ...

Crash when resizing window using Quad Stereo Buffer

UE - Virtual Production - nDisplay - Oct 2, 2019

We noticed crashes in our application when we attempted to resize a window or switch to full-screen mode. Hence, resizing windows and switching to full screen will result in a crash on Unreal Engine ...

Crash Importing some assets with "Keep Overlapping Vertex"

UE - Editor - Content Pipeline - Import and Export - Nov 29, 2016

Download offending asset here: [Link Removed] Error message: Assertion failed: NewPosition >= 0 [Link Removed] [Line: 452] Source Context: 438 virtual ~FFileHandleWindows() 439 ...

Editor Crashes When Updating Captures on Sphere Reflection Captures

UE - Graphics Features - Feb 20, 2017

Error message: Assertion failed: (Index >= 0) & (Index < ArrayNum) [Link Removed] [Line: 633] Array index out of bounds: -1 from an array of size 11 Source Context: 200 CubemapArray.Updat ...

The pak file specified in PakFileRules is not created correctly

UE - CoreTech - Aug 8, 2023

The rules by which chunks are created are ambiguous and currently do not ensure that both PakFileRules and PrimaryAssetLabel settings are reflected. In this sample, depending on the PrimaryAssetLabe ...

Crash Occurring in FD3D11DynamicRHIModule::FindAdapter()

UE - Graphics Features - Jul 13, 2016

Error message: Assertion failed: (Index >= 0) & (Index < ArrayNum) [Link Removed] [Line: 804] Array index out of bounds: 1 from an array of size 1 Source Context: 352 353 // We a ...