Division by zero causing NaN/Inf on USkeletalMeshComponent::UpdateRigidBodyScaling() when setting scale to zero and back

UE - Simulation - Core - Feb 11, 2026

Up to UE 5.5, skeletal mesh physics did not get updated when the component's scale changed. This was improved on January 2025 with CL 39190335, which addressed [Link Removed] ...

Enum Compare Condition causes crash when resetting default value of right field in State Tree's Enter Conditions

UE - AI - StateTree - Feb 11, 2026

In FStateTreeCompareEnumCondition::GetDescription, the Left.Enum value is mistakingly used when setting the RightValue. This causes crashes when resetting the default value of the Right field in an ...

FDetailGroup::AddGroup does not correctly apply the default expansion state for DetailGroups

UE - Editor - Workflow Systems - Feb 10, 2026

There is a bug affecting DetailGroups in the engine. When adding child DetailGroups to a parent DetailGroup, the expansion state does not behave as expected and ignores the flags intended to control ...

Directly opening a modified map asset of a streaming sublevel does not always force it to be reloaded (inconsistent with other map open behaviors)

UE - World Creation - Worldbuilding Tools - Feb 10, 2026

When the level currently being edited has unsaved changes and the user opens a new one, the Editor asks if the changes should be saved. If the user answers negatively, the level asset is reverted to ...

Client disconnected due to MissingLevelPackage in editor with Iris and server streaming enabled

UE - World Creation - Worldbuilding Tools - World Partition - Feb 9, 2026

When connecting to the server, if the client activates some local cells while the connection is still pending, ULevelStreaming::IsConcernedByNetVisibilityTransactionAck will return false. In this ca ...

MRG - Additional Post Process Render have a black alpha channel

UE - Virtual Production - Tools - MRQ - Feb 7, 2026

Additional Post Process renders always have a black alpha channel ...

"Could not find static actor" errors on standalone editor client when connecting to PIE server

UE - Networking - Iris - Feb 4, 2026

This seems to be due to how FObjectReferenceCache and UEngineReplicationBridge handle remapping object paths for PIE. When creating the object reference handle, the object’s path should get renamed ...

DynamicMaterialParameters Niagara module resets write flags on emitter update

UE - Niagara - Feb 4, 2026

When using the DynamicMaterialParameters Niagara module in UE 5.6, 5.7, and UE5-Main (CL 50298778), updating an emitter causes Boolean values, such as Index0Float0Write, to reset to default values, ...

Changing the ComponentClass of a ACharacter twice and trying to set a SkeletalMeshAsset crashes the engine

UE - Anim - Jan 22, 2026

Changing the ComponentClass of a ACharacter twice and trying to set a SkeletalMeshAsset crashes the engine with a "Cannot replace existing object of a different class" message. The conditions to re ...