Why Can't Discourse Retrieve OpenGraph Data?

[wlandgraf (Wagner Landgraf)]

When writing in topics in our Discourse site, when pasting some links, Discourse cannot retrieve OpenGraph (OneBox) information. We get an error like this (see also in screenshot):

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

However, the mentioned link is providing such information. It can be checked with the open graph.xyz site: https://www.opengraph.xyz/url/https%3A%2F%2Fwww.tmssoftware.com%2Fsite%2Fblog.asp%3Fpost%3D1069

Actually it even works here, in Meta Discourse, here is the link and it shows correctly:

Offline maps in TMS FNC Maps for Delphi

Any reason why this might be happening, and is there a way to see some logs about what Discourse is actually receiving from our server when calling this URL?

[Lilly]

@wlandgraf

When writing in topics in our Discourse site, when pasting some links, Discourse cannot retrieve OpenGraph (OneBox) information. We get an error like this (see also in screenshot):

Hi there - i tested that particular link you posted and it oneboxes as expected. clearly this is specific to your forum. do any oneboxes work at all? if so, are there any clues that can differentiate between oneboxes that work and ones that do not?

also, make sure your Discourse instance is up to date, and maybe check your onebox settings and have a look at this topic?

Configuring and troubleshooting oneboxes

This guide explains how to configure and troubleshoot oneboxes in Discourse. It covers admin settings, how oneboxes work, and steps to resolve common issues. Required user level: Administrator Oneboxes are rich link previews that users can create in their posts. While users can easily generate these previews, site administrators have additional controls and may need to troubleshoot when links don’t preview as expected. Admin configuration To manage onebox s…

[wlandgraf (Wagner Landgraf)]

@Lilly thank you for your response.

1. I have version `2026.01.0-latest`. I can update to `2026.2.0` of course, but my version is not that old.
2. Yes, all other oneboxes work in my forum. Just that ones don’t work.
3. About my onebox settings, they are all default. If I click “Only show overriden” nothing appears.

@Lilly

if so, are there any clues that can differentiate between oneboxes that work and ones that do not?

That was kind of one of my questions: is there a way to see (a log) exactly how Discourse is receiving the data from our server? I read somewhere that this is done server-side, not by the browser, so is there a way to check how Discourse is reading our page information?

[wlandgraf (Wagner Landgraf)]

Ok, I found the problem, it looks like Discourse server doesn’t have the recent certificate chain used by the server.