Connection timed out after 30000 milliseconds (ERROR 28)

API and Webhooks Authentication
1

API Endpoint(s) and/or Zoom API Event(s)

  • POST [https://zoom.us/oauth/token](https://zoom.us/oauth/token)

  • GET [https://api.zoom.us/v2/users](https://api.zoom.us/v2/users)

Description

We are a high-volume user of the Zoom API, executing this exact authentication and user-fetching workflow thousands of times a day without any issues.

However, we are hitting intermittent, critical windows where all API calls suddenly fail simultaneously with a connection timeout (Error 28). Our application runs in a local Linux environment using PHP and native cURL. During these specific windows, every single request times out after exactly 30 seconds (matching our CURLOPT_TIMEOUT), failing to receive any bytes, before the connection eventually recovers on its own.

Because it works flawlessly at scale 99% of the time, we want to check if Zoom’s Web Application Firewall (WAF) or edge infrastructure is occasionally flagging or throttling our IP block during these specific intervals, or if there were documented regional routing anomalies.

The most recent total outage windows occurred on:

  • Tuesday, May 3rd between 16:19 – 16:37 (Asia/Jerusalem time)

  • Wednesday, May 4th between 18:15 – 18:50 (Asia/Jerusalem time)

Error?

We are seeing two recurring timeout logs during these failure windows:

Plaintext

2026-05-03 16:30:31.10 (Asia/Jerusalem) - POST {"grant_type":"account_credentials","account_id":"***REDACTED***"} https://zoom.us/oauth/token (HTTP 0) Connection timed out after 30000 milliseconds (ERROR 28)

Plaintext

2026-05-03 16:31:33.45 (Asia/Jerusalem) - GET [] /users/ (HTTP 0) Operation timed out after 30001 milliseconds with 0 out of 0 bytes received (ERROR 28)

How To Reproduce

1. Request URL / Headers / Body

  • Auth Request:

    • URL: [https://zoom.us/oauth/token](https://zoom.us/oauth/token)

    • Method: POST

    • Body: {"grant_type":"account_credentials","account_id":"YOUR_ACCOUNT_ID"}

    • Headers: Authorization: Basic [BASE64_ENCODED_CLIENT_ID_AND_SECRET], Content-Type: application/x-www-form-urlencoded

  • Data Request:

    • URL: [https://api.zoom.us/v2/users](https://api.zoom.us/v2/users)

    • Method: GET

2. Authentication method or app type

  • Server-to-Server OAuth via PHP cURL on a local Linux development machine (running high-volume daily requests).

3. Any errors

  • HTTP 0 with Connection timed out after 30000 milliseconds (ERROR 28)

Official Zoom support will be much appreciated.

Thanks,

Tom

Open University of Israel