Calling FHttpResponsePtr::GetContentLength() from OnRequestProgress delegate returns different values on Mac/iOS than Windows

Tools - Nov 9, 2016

Licensee was looking for a way to get total file size to display download progress. On Windows (which uses the curl library for Http request/response), binding a function to the OnRequestProgress d ...

NPC - Instances does not get updates from changes to the parent Niagara Parameter Collection in the editor

UE - Rendering - Architecture - Niagara - Oct 4, 2024

When an Niagara Parameter Collection (NPC) is selected as the parent Collection for an NPC Instance (NPCI), all of its current parameters are carried over to the NPCI with their current values as th ...

For a TMap with C++ enum keys, deleting and re-adding a map entry in the Editor can corrupt the map data.

UE - Editor - Jul 19, 2024

When adding an entry to a TMap using UE's property editors, in most cases the new entry comes with a default-initialized key (if such key already exists, the insertion fails). The case of a UENUM de ...

Crash (Assertion failed "SystemInstanceController->IsSolo()") when enabling "Start with Tick Enabled" on a Niagara Component

UE - Rendering - Architecture - Niagara - Oct 17, 2024

Currently, Niagara Components are only expected to have their TickComponent() method called when their system is marked as "Solo", which makes them be simulated individually. In the most common scen ...

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 ...

Input Actions bound to Any Key become unresponsive after mouse scroll until scrolled again

UE - Gameplay - Input - Mar 28, 2025

In UE latest release (5.5 launcher version), Enhanced Input Actions mapped to "Any Key" stop responding after scrolling the mouse wheel. Specifically, scrolling either up or down disables the Any Ke ...

Sequence with restore state set is causing a "Fatal world leaks detected" crash

zComponent - Archive - May 14, 2025

We recently had a few occurrences of crashes caused by a "Fatal world leaks detected" error when unloading a level (in a packaged game and in editor). I tracked down what was keeping a references t ...

[CrashReport] UE4Editor_Engine!UModelComponent::CommitSurfaces() [modelcomponent.cpp:163]

UE - LD & Modeling - Modeling Tools - BSP - Oct 26, 2017

This is a somewhat common crash that has existed since at least 4.14.. It appears related to an Undo operation on geometry. User DescriptionsUndoing a move of a boxbrush wall and staircaseundoing i ...

The CompileAllBlueprintsCommandlet does not list the BPs contained in UWorlds

UE - Framework - Blueprint - Dec 16, 2024

hThe use case of the licensee is that he used FindInBlueprints inside the Editor to find a particular text contained in BPs and later used that listing to recompile the BPs using the CompileAllBluep ...