Building a website that requires sharing links with an image. Done this I don\'t know how often...but this time the Facebook Open Graph Debugger says:
og:image {image ur
I experienced this problem today.
Since the developer link to a bug in the other answer says that the problem was fixed, I thought I would provide information about the issue I experienced.
The fact is that my website is expected to be used on HTTPS (with SSL) and not HTTP. I give the tool an address with, clearly, HTTPS everywhere (all URLs on the page are HTTPS and the one I paste in the Sharing Debugger is also HTTPS). Yet, they ended up failing because in their test, somehow, they drop the "S" and hit the server without any encryption.
I thought that could help some other people. By enabling the non-encrypted website, Facebook started working since everything was in place (and it was for a while, but that error was driving me crazy!)