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Alana Storm
Alana Storm

Reputation: 166166

Facebook's Default Image When `og:image` is Invalid

How does Facebook choose a preview image when the og:image tag is invalid? A friend and I were curious why a Facebook preview image didn't show up in the article — when we ran the URL through the Facebook debugger, it provided the following information.

Provided og:image could not be downloaded or is not big enough. Please use an image that's at least 200x200px and is accessible from Facebook. Image 'http://lostoregon.files.wordpress.com/2014/06/foodcarts.jpeg' will be used instead

Tangent: Running the debugger once appears to clear Facebook's cache, and on the next run Facebook grabbed the correct (since fixed?) image.

The one part of this I don't understand is: How did Facebook chose the http://lostoregon.files.wordpress.com/2014/06/foodcarts.jpeg image to use instead? When I look at the original page, foodcarts.jpeg isn't shown anywhere, which means either

  1. Facebook has some secret sause for chosing from images it's seen before

  2. Facebook picked an image that was on the page at the time, but is no longer there

  3. Something else I'm not considering

Is this default image picking defined, deterministic behavior? If so, how does it work?

Upvotes: 1

Views: 240

Answers (1)

tattvamasi
tattvamasi

Reputation: 825

the error you describe is common enough, and the image may be all right, but Facebook probably has issues downloading it (it's too big). What happens when the image isn't good is that the get a cached representation of you page, and use the image you provided back then. If Facebook crawls many urls, and there's no image on your site, or there's no cached image, the system will pick the one you use more frequently (on all pages). At least, that's what I have seen.

Upvotes: 1

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