This is a problem created by Mediawiki’s bad URL structure, but it happens occasionally on my sites. The URL of an HTML page for an image on Wikipedia works: If I paste this URL below without backticks, it will create a onebox (wrong title, but at least the link works): https://en.wikipedia.org/wiki/Main_Page#/media/File:ESO_Centaurus_A_LABOCA.jpg Result: en.wikipedia.org Main PageWelcome to Wikipedia During the 1998–99 English football season, Gillingham F.C. competed in the Football League Second Division, the third tier of the English football league system. It was the 67th season in which Gillingham competed in the Football League, and the 49th since the club was voted back into the league in 1950. The club signed two new forwards, each for a new club record transfer fee, but started the season in poor form, winning only one of the first eight league games. The team then went on a much-imp... If I do it with another Mediawiki site like this URL, it breaks the onebox: https://fortnite.fandom.com/wiki/Fortnite:_Save_the_World?file=Update+v40.20+-+Cover+Art+-+Save+the+World.jpg Result: Maybe it could be fixed by checking the Content-Type in the response for text/html ? If it is, then don’t treat it as an image?