declared-size.unusable
og:image:width or og:image:height is not a usable number. Level: Warning.
When it is raised
Raised when the card image loaded, both og:image:width and og:image:height have a value, and either value does not parse as a finite number greater than zero. Values such as 1200px, auto, 0, -630 or Infinity raise it. Tags are read in the first 300,000 characters of the HTML, outside comments, and only the first og:image:width and the first og:image:height that have a content attribute are read.
What it does to a shared link
The tags are present, but at least one of them does not state a usable number. The message shows the two values as found, with control characters removed, whitespace collapsed, and each cut to 16 characters, ending in an ellipsis where it was shortened.
How to fix it
- Set each tag to the image's dimension in whole pixels as a plain number, with no unit or other text.
- Check the first og:image:width and og:image:height in the page, since that is the pair this check reads, and remove any duplicates.
<meta property="og:image:width" content="1200">
<meta property="og:image:height" content="630">