# Error Code 1020 authentication issue

**URL:** <https://devforum.zoom.us/t/error-code-1020-authentication-issue/78427>\
**Category:** API and Webhooks\
**Created:** [November 7, 2022, 8:07pm UTC](https://devforum.zoom.us/t/error-code-1020-authentication-issue/78427 "2022-11-07T20:07:37Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![andrewb](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@andrewb](https://devforum.zoom.us/u/andrewb)\
**Post date:** [November 7, 2022, 8:07pm UTC](https://devforum.zoom.us/t/error-code-1020-authentication-issue/78427/1 "2022-11-07T20:07:38Z")

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* * *

**API Endpoint(s) and/or Zoom API Event(s)**  
[https://zoom.us/oauth/authorize?response\_type=code&client\_id=](https://zoom.us/oauth/authorize?response_type=code&client_id=)

**Description**  
My application authentication logic hasn’t changed, but it appears that starting after this weekend there was a firewall change or something related to Zoom’s cloudflare configuration. Any time I attempt to authenticate with the instructions listed here [OAuth with Zoom](https://marketplace.zoom.us/docs/guides/auth/oauth/), my server code is returning an error from cloudflare. Running this same call within a REST client like Postman/Imsomnia doesn’t have this issue. It is similar to other posts like this [Error Code 1020](https://devforum.zoom.us/t/error-code-1020/78374).

**Error?**  
error 1020

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<div class="post-metadata">

**Author:** ![andrewb](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@andrewb](https://devforum.zoom.us/u/andrewb)\
**Post date:** [November 7, 2022, 8:55pm UTC](https://devforum.zoom.us/t/error-code-1020-authentication-issue/78427/2 "2022-11-07T20:55:24Z")

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Doing some more testing, it seems that Zoom no longer supports HTTP/1.1 requests. Modifying to HTTP/2 seems to have fixed the denied issues from Cloudflare.

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**Author:** ![a.koval](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/a.koval/32/2585_2.png) [@a.koval](https://devforum.zoom.us/u/a.koval)\
**Post date:** [November 8, 2022, 11:33am UTC](https://devforum.zoom.us/t/error-code-1020-authentication-issue/78427/3 "2022-11-08T11:33:19Z")

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Awesome!

It fix my problem too.

Now I use option:

```auto
&http.Client{
		Transport: &http.Transport{
			ForceAttemptHTTP2: true,

```

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex016/uploads/zoomdeveloper/original/3X/6/1/614bdd549b610bbaa46ff934617683a02bdaa03c.png) [@system](https://devforum.zoom.us/u/system)\
**Post date:** [November 12, 2023, 3:10am UTC](https://devforum.zoom.us/t/error-code-1020-authentication-issue/78427/4 "2023-11-12T03:10:15Z")

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Closed on November 12, 2023, 3:10am UTC

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