# Canvas element freezes after media upload, works after switching tabs

**URL:** <https://discourse.mozilla.org/t/canvas-element-freezes-after-media-upload-works-after-switching-tabs/138914>\
**Category:** Firefox Development\
**Tags:** issue\
**Created:** [January 13, 2025, 7:27am UTC](https://discourse.mozilla.org/t/canvas-element-freezes-after-media-upload-works-after-switching-tabs/138914 "2025-01-13T07:27:48Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![deatheetu](https://avatars.discourse-cdn.com/v4/letter/d/bbce88/32.png) [@deatheetu](https://discourse.mozilla.org/u/deatheetu)\
**Post date:** [January 13, 2025, 7:27am UTC](https://discourse.mozilla.org/t/canvas-element-freezes-after-media-upload-works-after-switching-tabs/138914/1 "2025-01-13T07:27:48Z")

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Hey everyone, I’m running a Unity WebGL game and a browser application overlaid on top of the game canvas element. Whenever I upload a media file with the browser app, the game canvas becomes unresponsive. It’s like the element loses focus, but I’ve tested it manually and that’s not it.

However, visiting another tab or window causes the game to start running normally. Even a click on the browser console does the trick. I’m wondering what is happening in the background when switching away from the document, that might cause my app to start working again. Thanks in advance.

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**Author:** ![bjh](https://sea1.discourse-cdn.com/flex001/user_avatar/discourse.mozilla.org/bjh/32/21802_2.png) [@bjh](https://discourse.mozilla.org/u/bjh)\
**Post date:** [January 19, 2025, 8:29pm UTC](https://discourse.mozilla.org/t/canvas-element-freezes-after-media-upload-works-after-switching-tabs/138914/2 "2025-01-19T20:29:57Z")

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This forum doesn’t get much activity.

If you have a reproducible test case could you please report it in [Bugzilla](https://bugzilla.mozilla.org/).

Current public discussions are [in the Matrix](https://wiki.mozilla.org/Matrix). You can [join](https://wiki.mozilla.org/Matrix:Join) and talk with other users in #firefox:mozilla.org or talk with developers in #introduction:mozilla.org.