Have you ever tried to share a link Facebook, especially to a page on your own site, and the photo thumbnail doesn’t want to load in the Facebook post, even after reattempting several times hours later?
Usually this is because at the time you attempted to share the link, Facebook preloaded the link to obtain metadata and images from the submitted link, but for some reason it couldn’t load that image initially and timed out.
Often, if you try to repost the link hours later it still does not display a thumbnail image from the link. This is because Facebook is now simply loading all of that URL’s metadata from Facebook’s local cache.
Solution: Facebook has a debug tool for developers at https://developers.facebook.com/tools/debug, which accepts a URL and it will analyze that given URL for markup, metadata, and other tokens/assets at that URL.
The tool serves mainly to debug external pages as far as what Facebook can preload and present to Facebook users when it is (re)shared within Facebook.
But what this tool also does by virtue of debugging a URL is refresh Facebook’s local cache of that given URL, thereby attempting to reload images on the target URL that it couldn’t load the first time it tried to load it (and cached).
Comment on this post