Unity Issue Tracker - NullReferenceException error is thrown when adding the OverlayContainer or ToolbarOverlayContainer Element to the Hierarchy in UI Builder

Fixed

Fixed in 6000.2.0a7

Votes

Found in

Issue ID

Regression

NullReferenceException error is thrown when adding the OverlayContainer or ToolbarOverlayContainer Element to the Hierarchy in UI Builder

-

Mar 07, 2025

Steps to reproduce:

Open any Project
Create a UI Document Asset in the Project Browser and open it
In the Library choose "Project"
Add OverlayContainer or ToolbarOverlayContainer to the Hierarchy (from UxmlSerializedData > UnityEditor > Overlays)

Actual results: Error "NullReferenceException: Object reference not set to an instance of an object

UnityEditor.Overlays.OverlayContainer+UxmlSerializedData.Deserialize (System.Object obj) (at <020c0befcaf54273ae8e5ac79216d210>:0)"

logged in Console when the Overlay Container is added to the UI Docs Hierarchy

Artifacting happens when Further adding anything to the Hierarchy and other errors are logged

Expected results: No issues with Elements

Reproducible with versions: 2023.3.0a15, 6000.0.42f1, 6000.1.0b10, 6000.2.0a6

Not reproducible with versions: 2022.3.60f1, 2023.3.0a14

Tested on (OS): Windows 11