Have you ever posted a personal URL in a new status on Facebook only to realize the auto-populated information is not what you expected?
Sometimes it grabs an image you don’t like or you realize that the page title has a typo… any number of things can go wrong.
It’s pretty easy to ditch the new status, go adjust your web page, then start over with another status.
The problem is Facebook caches what you’ve posted. So when you try to post the URL again after making your adjustments and you can’t seem to “fix” the original mistake, this is why.