# Detect and report Oneboxer failure due to CloudFlare

**URL:** https://meta.discourse.org/t/detect-and-report-oneboxer-failure-due-to-cloudflare/388446
**Category:** Feature
**Created:** [November 14, 2025, 3:25am UTC](https://meta.discourse.org/t/detect-and-report-oneboxer-failure-due-to-cloudflare/388446 "2025-11-14T03:25:25Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![supermathie](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/supermathie/32/507518_2.png) [@supermathie](https://meta.discourse.org/u/supermathie)
#### Post date: [November 14, 2025, 3:25am UTC](https://meta.discourse.org/t/detect-and-report-oneboxer-failure-due-to-cloudflare/388446/1 "2025-11-14T03:25:25Z")

</div>

When the Oneboxer is blocked by CloudFlare, it would be a much better user experience if instead of:

> Sorry, we were unable to generate a preview for this web page, because the following oEmbed / OpenGraph tags could not be found: image, title

Discourse revealed the actual problem to users:

> Sorry, CloudFlare prevented Discourse from generating a preview for this web page.

Concept screenshots:

> ![image](https://global.discourse-cdn.com/meta/original/4X/6/7/f/67fab889fe2a4f62edfd4f16551ab484b5980e86.png)  
> (before)

> ![image](https://global.discourse-cdn.com/meta/original/4X/c/d/9/cd997f5d2affdb769ac076a116023f33c20fe166.png)  
> (after)

This could be detected by the presence of a `cf-mitigated: challenge` header in the 403 response as per [Detect a Challenge Page response · Cloudflare challenges docs](https://developers.cloudflare.com/cloudflare-challenges/challenge-types/challenge-pages/detect-response/)