Problem making a scrolling menu ui...

I want a menu of UI objects, and there will be enough of these objects that I'll need to scroll. They are dynamically generated, though I don't think that matters to my question.

I have a scroll view, and on its "content" object I've added a VerticalLayoutGroup and a ContentSizeFitter. But this is throwing exceptions, despite being the same method shown in this video, without errors

It throws between 4 and 10 identical exceptions the first time these components are enabled, and every time I make a change to that canvas, but doesn't seem to affect functionality (ie it still works). The exceptions look like this:

 Trying to add (Layout Rebuilder for) Content (UnityEngine.RectTransform)
 for layout rebuild while we are already inside a layout rebuild loop.
 This is not supported.
 UnityEngine.Canvas:SendWillRenderCanvases()

To reiterate, the menu functions as you would expect. Removing either Component breaks the functionality, but using them both causes these errors every time I press Play.