# Uncaught ReferenceError: localJsonpCallback is not defined using zoom web sdk

**URL:** <https://devforum.zoom.us/t/uncaught-referenceerror-localjsonpcallback-is-not-defined-using-zoom-web-sdk/20640>\
**Category:** Web\
**Created:** [June 8, 2020, 11:51am UTC](https://devforum.zoom.us/t/uncaught-referenceerror-localjsonpcallback-is-not-defined-using-zoom-web-sdk/20640 "2020-06-08T11:51:20Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![rahul4](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/rahul4/32/7332_2.png) [@rahul4](https://devforum.zoom.us/u/rahul4)\
**Post date:** [June 8, 2020, 11:51am UTC](https://devforum.zoom.us/t/uncaught-referenceerror-localjsonpcallback-is-not-defined-using-zoom-web-sdk/20640/1 "2020-06-08T11:51:20Z")

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@tommy  
@ojus.zoom

I am using 1.7.8 version zoom web sdk.

I am using pro account.  
At first, the join of ZoomMtg gives error but after retry joins.  
This happens everytime and it is frustating for client. There is no internet issue.

Please find the screenshot for the same.

 ![Screen Shot 2020-06-08 at 5.01.26 PM](https://us1.discourse-cdn.com/flex016/uploads/zoomdeveloper/original/2X/f/fc4d12bd9126c6e09ae508f694071fdb05e4a010.png)

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**Author:** ![tommy](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/tommy/32/72769_2.png) [@tommy](https://devforum.zoom.us/u/tommy)\
**Post date:** [June 12, 2020, 8:38pm UTC](https://devforum.zoom.us/t/uncaught-referenceerror-localjsonpcallback-is-not-defined-using-zoom-web-sdk/20640/2 "2020-06-12T20:38:40Z")

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Hey @rahul4,

Make sure you allow time for the [Web SDK files](https://marketplace.zoom.us/docs/sdk/native-sdks/web/getting-started/integrate) to load before joining a meeting.

```auto
ZoomMtg.preLoadWasm();
ZoomMtg.prepareJssdk();

```

You can check the network tab to see if you are joining the meeting before the Web Assembly files have loaded.

Thanks,  
Tommy

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**Author:** ![rahul4](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/rahul4/32/7332_2.png) [@rahul4](https://devforum.zoom.us/u/rahul4)\
**Post date:** [June 15, 2020, 7:01am UTC](https://devforum.zoom.us/t/uncaught-referenceerror-localjsonpcallback-is-not-defined-using-zoom-web-sdk/20640/3 "2020-06-15T07:01:50Z")

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@tommy

I used a set timeout of 10 sec for calling ZoomMtg.init, still the issue exists. The clients have a high network speed of 30mb/sec. Still, they are facing the above issue.

Please help.

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**Author:** ![tommy](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/tommy/32/72769_2.png) [@tommy](https://devforum.zoom.us/u/tommy)\
**Post date:** [June 18, 2020, 6:54am UTC](https://devforum.zoom.us/t/uncaught-referenceerror-localjsonpcallback-is-not-defined-using-zoom-web-sdk/20640/4 "2020-06-18T06:54:35Z")

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Hey @rahul4,

Please send me a github repo link with steps to reproduce the issue so I can test and debug locally.

Thanks,  
Tommy

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**Author:** ![DeveloperBot](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/developerbot/32/12632_2.png) [@DeveloperBot](https://devforum.zoom.us/u/DeveloperBot)\
**Post date:** [August 21, 2020, 10:07pm UTC](https://devforum.zoom.us/t/uncaught-referenceerror-localjsonpcallback-is-not-defined-using-zoom-web-sdk/20640/5 "2020-08-21T22:07:37Z")

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