# VideoSDK-Web - iOS video flickering & WebGL errors

**URL:** <https://devforum.zoom.us/t/videosdk-web-ios-video-flickering-webgl-errors/113125>\
**Category:** Video SDK\
**Created:** [July 5, 2024, 12:56pm UTC](https://devforum.zoom.us/t/videosdk-web-ios-video-flickering-webgl-errors/113125 "2024-07-05T12:56:33Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![fides-it](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/fides-it/32/51395_2.png) [@fides-it](https://devforum.zoom.us/u/fides-it)\
**Post date:** [July 5, 2024, 12:56pm UTC](https://devforum.zoom.us/t/videosdk-web-ios-video-flickering-webgl-errors/113125/1 "2024-07-05T12:56:33Z")

</div>

# Setup

Video SDK for Web 1.11.6  
iPhone 15 Pro - iOS 17  
+/- 8 participants in the call, video-player setup with one canvas.

On Safari the videos of the participants start flickering immediately and it won’t stop. I haven’t noticed this before. I’m observing these errors:

WebGL: INVALID\_OPERATION: uniform4f: location not for current program  
WebGL: INVALID\_OPERATION: uniform1i: location not for current program

See below video:

[![](https://us1.discourse-cdn.com/flex016/uploads/zoomdeveloper/original/3X/a/c/ace5d411b80631010da1872713366568dff3185e.jpeg "iOS Safari WebGL Errors Flickering") ](https://www.youtube.com/watch?v=devvWjU4VeU)

I’ve seen this behavior on two different iPhones (my own and on Lambdatest)  
Any idea what’s going on & how to fix it?