What to do when Facebook link preview won't work

A few days ago, I was having problems sharing one of my blog posts on Facebook. No matter what I did, the link preview wasn't automatically appearing. To fix the problem, I just manually edited the Facebook post. But that doesn't really fix the problem for future shares of the exact same post.

I rechecked the link to see if it would generate normally if someone else were to share the post at a later time: it still had the same problem of not generating the preview. So I scoured the bowels of Google to find a solution. I found this explanation (http://www.marketingyourpurpose.com/facebook-link-preview-not-working/) of an alternative to manually editing the post. It led me to the Facebook Sharing Debugger (https://developers.facebook.com/tools/debug/).

The page looks like this (the author of the source noted that the debugger tool isn't originally intended for this purpose, but it still works):

Here's what you do: you enter the link in the bar and click on "debug". I had to click the "debug" button twice because the link preview still didn't show up properly after the first time I clicked it (there's a spot on the page, after clicking "debug", that shows what the link would look like on a Facebook post).
A lot of different technical stuff also loads on the page, but I ignored those. The main focus is to check if the link preview generates properly.

Hope this helps if ever the link you're trying to share on Facebook won't render a preview!