# 400 Errors followed by HTML Payload! - On valid request

**URL:** <https://devforum.zoom.us/t/400-errors-followed-by-html-payload-on-valid-request/107046>\
**Category:** API and Webhooks\
**Created:** [April 2, 2024, 11:04pm UTC](https://devforum.zoom.us/t/400-errors-followed-by-html-payload-on-valid-request/107046 "2024-04-02T23:04:33Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![zoommeeting](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/zoommeeting/32/18751_2.png) [@zoommeeting](https://devforum.zoom.us/u/zoommeeting)\
**Post date:** [April 2, 2024, 11:04pm UTC](https://devforum.zoom.us/t/400-errors-followed-by-html-payload-on-valid-request/107046/1 "2024-04-02T23:04:33Z")

</div>

**API Endpoint(s) and/or Zoom API Event(s)**  
/webinars/{webinarId}/registrants

**Description**  
This API is being used to register webinar attendees. Most of the time it works perfectly but every so often today it returns a 400 error which is often followed by massive payloads which appear to be Zoom web pages!

This is a log of part of the returned payload after a failure:

Content-Type: application/json  
Content-Length: 158  
Authorization: Bearer XXXXX (where XXXXX is an exact match to the OAUTH token received immediately prior to this call)  
  
senddoc(): entered  
{ json payload }  
recvresp(): entered  
HTTP/1.1 400 Bad Request

**/// More cookie stuff then this payload arrives!**

chunk size = 3430  
get\_chunk\_size returned 3430  
calling comm\_blockread

```auto
<!doctype html>
--snip--
<html xmlns:fb="http://ogp.me/ns/fb#" lang="en-US">
<head prefix="og: http://ogp.me/ns# fb: http://ogp.me/ns/fb# zoomvideocall: http://ogp.me/ns/fb/zoomvideocall#">
<title>Error - Zoom</title>
<meta http-equiv="X-UA-Compatible" content="IE=edge,Chrome=1">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="referrer" content="origin-when-cross-origin">
<meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1.0">

```

```auto

I have no idea where to even begin to look for the source of this problem.
```

---

<div class="post-metadata">

**Author:** ![zoommeeting](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/zoommeeting/32/18751_2.png) [@zoommeeting](https://devforum.zoom.us/u/zoommeeting)\
**Post date:** [April 4, 2024, 5:15pm UTC](https://devforum.zoom.us/t/400-errors-followed-by-html-payload-on-valid-request/107046/2 "2024-04-04T17:15:58Z")

</div>

Nobody else seen this behaviour? No one from Zoom with any thoughts?

---

<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:** [April 8, 2025, 8:52am UTC](https://devforum.zoom.us/t/400-errors-followed-by-html-payload-on-valid-request/107046/3 "2025-04-08T08:52:35Z")

</div>

Closed on April 8, 2025, 8:52am UTC

This topic was automatically closed 368 days after the last reply. New replies are no longer allowed.