ResizeObserver loop completed with undelivered notifications.

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Good day everyone,We have been receiving an error in Mendix version 11.6.2 that says:“ResizeObserver loop completed with undelivered notifications.”I haven’t been able to identify the source of this error yet. Does anyone have an idea what might be causing it or what the possible solution could be?I have read some information on this website: TrackJS I wanted to check if anyone else has experienced the same issue.Thanks in advance.
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3 answers
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Hi,


This warning is typically not a Mendix-specific issue but comes from the browser’s ResizeObserver API. It usually occurs when a component continuously triggers layout changes (resize → render → resize loop).

In Mendix 11 (React client), this is commonly caused by:

  • Layout Grids or containers with dynamic height/width changes
  • Widgets inside scrollable containers recalculating size repeatedly
  • Custom widgets or charts reacting to size changes on every render

Recommended approach to resolve:

  1. Avoid continuous layout recalculations
  2. Check for containers using:
  • height: auto combined with dynamic content
  • Nested scroll containers (overflow: auto/scroll)

Try simplifying the layout or fixing height where possible.

  1. Review custom or third-party widgets
  2. If you are using charts, maps, or custom React widgets:
  • Ensure they are not triggering resize updates on every render
  • Add throttling/debouncing if applicable
  1. Check visibility conditions
  2. Frequent show/hide (conditional visibility) can trigger repeated reflows.
  3. Try to avoid rapid toggling of containers.
  4. Upgrade widgets / Mendix version
  5. Some older widgets are not fully optimized for React client.
  6. Updating to the latest widget versions or Mendix patch release often resolves this.
  7. Safe to ignore (in many cases)
  8. If this appears only in the browser console and does not impact UI behavior, it is generally safe to ignore. It is a known browser-level warning seen in React-based apps.


This is usually caused by a resize-render loop in the UI rather than a backend issue. Optimizing layout structure and avoiding unnecessary re-renders typically resolves it.


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Hi Selcuk Emre

This is a generic issue which raises due to UI element is reacting to its own size changes, causing an infinite resize loop. Basically your browser detect this anamoly and stop it-> this sends the alert which you say in mendix.


Mostly likely you have to check the UI for the element from which page your getting this.

This usually happens when:

  • A widget has auto height/width
  • AND it sits inside a dynamic layout (flex/grid/data view)
  • AND it re-renders based on size or content


Let me know if it helps!


answered