Allow sub-domains from blocked domain to onebox

On a site I help run, we’ve recently found that a certain site fails to onebox (becomes a large empty space). We would have just blocked the domain from oneboxing, but that breaks oneboxing the forum hosted at a sub-domain of that site. Is it possible for us to allow the sub-domains to onebox without allowing the top domain to onebox?


For example, this main-site onebox fails (

But the subdomain (Discourse) is fine (


unfortunately i don’t think that is possible as per this topic

There seems to be something off with the link that creates the giant blank space. In the preview I notice it tries to give a big ‘Replit’ logo image. Could it be that the image used on those type of pages is breaking the onebox? Sorting that out may help them resolve nicely.

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There’s a specific script for Replit oneboxes:

When we paste a Replit link, the composer shows the expected result:

When the post is processed, the link is transformed into an empty iframe.

<iframe width="695" height="521" frameborder="0" data-unsanitized-src="" seamless="seamless" sandbox="allow-same-origin allow-scripts allow-forms allow-popups allow-popups-to-escape-sandbox allow-presentation">

I don’t know if the issue comes from Replit or from the onebox script. I’d guess it’s the script, but I’m no coder :slight_smile:

The link has proper opengraph tags, though: Sharing Debugger - Meta for Developers