OpenGraph images should use og:image:url instead of og:image

However, both the official Open Graph documentation and Facebook's documentation both say that og:image is valid:

• http://ogp.me
• https://developers.facebook.com/docs/sharing/webmasters
• https://developers.facebook.com/docs/sharing/best-practices

By multiple images the order of the meta tags sholud be:

• og:image (image1)
• og:image:url (image1)
• og:image:type (image1)
• og:image:width (image1)
• og:image:height (image1)
• og:image (image2)
• og:image:url (image2)
• og:image:type (image2)
• og:image:width (image2)
• og:image:height (image2)

and og:image:url - Identical to og:image.

Pinterest also demands image_url

@YIY: Per Pinterest's documentation:

og:image - URL for a high resolution image for the article. Up to 6 og:image tags can be provided.

If anyone can show documentation from a service to indicate actual requirements I'll be happy to hear it and will update the UI accordingly, but I can't find anything to back up this request.

Ah, just found this, posted a possible solution to a duplicate to this issue at https://www.drupal.org/node/2473107#comment-9875629. While reading through this - the diverging of documentation and issue may have another cause. In my case I had to fight Byte Order Marks first, for example, and a div container I had placed and forgotten in html.tpl.php for testing purposes. At least, removing these plus the change I proposed in the linked comment fixed the issue for me.

Marking this as a duplicate of #2473107: Getting "required property 'og:image:url' of type 'url' was not provided." error on Facebook Debugger. FYI I added a small note to the og:image:type field indicating that there must be the same number of images as 'type' values, otherwise the validator will give an error.