Bug Unknown type: 'Unity.UI.Builder.UnityUIBuilderSelectionMarker'

Project contains:
VisualElement with Grow=1
Button inside VisualElement

This is very inconsistent bug. Build is made for Android and happens only on the actual device.

As you can see in the image, the error text appears on the bottom of the screen. When something is changed in the project it might dissapear with another build. For example, I changed grow to 0 and then back to 1, made a new build and issues dissapeared. This issue might occurs at any screen with any random elements in it.

Unity: 2021.2.9f1

 

Ha, just got this on a mac build

 

To be more explicit, I get this on a Mac build and does not appear on the PC build. I don't know what should be including this or why or where

 

I've got this also on WebGL build (2021.3.0f1), additionaly a browser console outputs something like this:
"Element 'Unity.UI.Builder.UnityUIBuilderSelectionMarker' has no registered factory method."



EDIT: New build after restarting Unity helped.

 

Hi, any update on that? I started receiving the same error message.

 

I had the same error out of nowhere on an empty project in Unity 2021.3.19f1.

I've tried to restart Unity and make a new build but that did not work for me. I've tried to remove the "UI Document" Component from my Scene. Then I made a new build and I added it again. This fixed it for me.

 

The Error Message did dissapear in my project after creating a "New" unsaved file inside the Ui Builder and closing the Builder without saving , i guess that cleaned up any left over helper variables of that builder tool.

 

For me, this was an issue of not specifying a namespace for the button. I guess there's another Button class defined somewhere in my solution and I needed to write it as "<ui:Button/>" for it to start working. Perhaps Odin Inspector defines Button as well. Dunno, but that fixed it for now.