ResizeObserver JavaScript(?) error


V14.11.8. (99% java FWIW)

Important: I am a classic “Swing-to-Vaadin” guy, so clueless about JavaScript.

Recently (1-2 months?) I regularly see “ResizeObserver loop completed with undelivered notifications”. F5 fixes it.

I thought it was only on my dev system, but it turns out it regularly (but not always) appears on customer screens immediately after logging in. (Each of ~30 customers are hosted on their own VPS)

I have searched my code base (~70k lines) for anything to do with “size”, “resize” and listeners etc, but I can find nothing obvious.

In the forum “ResizeObserver” is mentioned once (Feb 2023), but that turned out to be a Vaadin bug that was then fixed.

I have never seen this in my Intellij debugger (with a MOCK backend) - so I have no example project I can offer.

Are there any suggestions on how to identify/debug/workaround/suppress this issue?

Any and all ideas are appreciated.


ResizeObserver is JavaScript API in modern browsers to hook to element size changes (usually due Browser window size changes, but not limited to that). Vaadin 14 did not use that, as it was supposed to work also with IE11 and the stock components actually use IronResize behavior which is a bit different. This makes me believe that you have some add-on component from Directory in use, which uses ResizeObserver for something and the problem is there.

Thx Tatu. That gives me a few clues. I’ll start disabling the add-ons and see what I find. I appreciate your response.