Unreal Engine Issues
Unreal Engine Issues
WorldPartitionConvertCommandlet hits an assert when converting a persistent level that contains a sub-level with a landscape
UE - World Creation - Worldbuilding Tools - Nov 7, 2025Context: The Window tab allows a user to open the Levels window in order to add a sub-level to a persistent level. For Unreal Engine 5.0 and beyond, World Partition has made the Levels window obsole ...
UNetDriver server-side hitch results in ActorInfo->NextUpdateTime far into future
UE - Networking - Feb 16, 2024A high UWorld::Tick DeltaSeconds (i.e. GameThread hitch) results in a high UNetDriver::TickFlush DeltaSeconds. This DeltaSeconds can high (many seconds) if the hitch is long. This value then affects ...
Niagara - When Interpolated Spawning is disabled, the first frame of each particle unexpectedly does not take into account the Particle Update stage
UE - Niagara - Feb 28, 2025Foreword: Even if the behavior described here is by design, it is rarely (if ever) expected or desired. This was discussed and agreed to be treated as a bug. Explanation below. When interpolated sp ...
Chaos Fields: LS_MasterField continuously creates components every frame and never cleans them up
UE - Simulation - Visual - Mar 25, 2026While active and ticking, the built-in FS_MasterField actor instance continuously creates several new components every frame, which are never cleaned up until the actor is destroyed. This can happen ...
Velocity Scene Texture Data Integrity Issues
UE - Graphics Features - Jan 8, 2026When a Post-Process Material uses the Scene Texture Material Expression, the following code is generated: ``` MaterialFloat2 Local0 = Parameters.TexCoords[0].xy; MaterialFloat2 Local1 = ClampSceneT ...
Blueprint with Niagara System and Skeletal Mesh Components Automatically Updates Niagara System Skeletal Mesh
UE - Niagara - Apr 4, 2019When adding a niagara system that reproduces a skeletal mesh and a skeletal mesh as components to a blueprint, the niagara system immediately updates its skeletal mesh to the most recently updated s ...
Crash when removing and re-adding instances to an InstancedStaticMeshComponent with PerInstanceCustomData.
UE - World Creation - Worldbuilding Tools - Jan 22, 2026When using an InstancedStaticMeshComponent with PerInstanceCustomData, the number of float elements in the "Custom Data" array should always be equal to NumCustomDataFloats multiplied by the number ...
Shader compiler errors when using enclosed local variables in a material while ray tracing is enabled
UE - Rendering - Architecture - RHI - Jan 23, 2020A licensee is seeing an issue with a couple of post process materials after enabling ray tracing. While the materials presenting the issue fail to compile for different reasons, they both refernce t ...
Memory leak when Lumen is disabled but r.MeshCardRepresentation=1
UE - Rendering - Graphics Features - Lumen - Jul 29, 2024When Lumen is disabled, but the cvar "r.MeshCardRepresentation" is set to 1, Lumen will continuously enqueue object removal from the Lumen Scene, without ever emptying the array of primitives to rem ...
Attempting to set skeletal mesh on vehicle blueprint during PIE crashes editor
UE - Simulation - Physics - Feb 8, 2016Switching the skeletal mesh of an actor during PIE crashes the editor. Frequency: 5/5 Crashreporter: N/A ...