# Mobile navigation bar dropdown throws console error on close

**URL:** <https://meta.discourse.org/t/mobile-navigation-bar-dropdown-throws-console-error-on-close/321047>\
**Category:** Bug\
**Created:** [August 10, 2024, 6:11pm UTC](https://meta.discourse.org/t/mobile-navigation-bar-dropdown-throws-console-error-on-close/321047 "2024-08-10T18:11:01Z")\
**Posts on this page:** 1\
**Showing post:** 1

<div class="post-metadata">

**Author:** ![Alteras](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/alteras/32/582398_2.png) [@Alteras](https://meta.discourse.org/u/Alteras)\
**Post date:** [August 10, 2024, 6:11pm UTC](https://meta.discourse.org/t/mobile-navigation-bar-dropdown-throws-console-error-on-close/321047/1 "2024-08-10T18:11:01Z")

</div>

**Priority/Severity** :  
Very low - No discernible impact on UX. However, will give anyone working with the `addNavigationBarItem` pluginAPI a scare.

**Platform** :  
Reproduced in Firefox & Chrome in responsive mode, Mobile site view.  
Effect visible in sites with debug logging and in [safe mode](https://meta.discourse.org/t/53504?silent=true).

**Description** :  
When the user in mobile site view closes the navigation bar dropdown menu (either by click on a link or by clicking outside dropdown), Ember will throw an uncaught error in the console. There is no discernible impact on the actual functionality of the site.

```plaintext
Uncaught (in promise) Error: Assertion Failed: You attempted to remove a function listener which did not exist on the instance, which means you may have attempted to remove it before it was added.

```

The issue has been observed in a local dev env, in the Theme Creator site, both in [safe mode](https://meta.discourse.org/t/53504?silent=true).

**Reproducible steps** :

1. Go to any page with a navigation bar/dropdown (latest, top, etc.) in the mobile site
2. open the dropdown
3. close the dropdown (either by clicking outside the dropdown or by clicking on one of the links)

* * *

This is a very low priority bug with no impact to normal users. It did however give me a scare as I was working on adding a nav item via `addNavigationBarItem` pluginAPI and thought I had broken the world when it occurred.

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_[View the full topic](https://meta.discourse.org/t/mobile-navigation-bar-dropdown-throws-console-error-on-close/321047)._