If you've ever run into a situation where you have correctly set your site's meta tags, but the shared preview of your post is showing out of date/incorrect information, you may need to reset the cached images/data for your page(s) on the social networks.
Facebook (and other social networks like Twitter and LinkedIn) 'cache' specific data about your posts when they are first shared to the platform. The social networks store this information for usually around 30 days (although this can vary). So if you've made significant changes to your metatags, you may need to instruct the social networks to reset their cached data for your pages and get the most up-to-date information.
This article will walk you through how to reset the cached images for Facebook, Twitter, and LinkedIn.
Facebook has an excellent resource, the Facebook Sharing Debugger Tool that makes this quick and easy. Simply copy the URL of the page that's giving you trouble and paste it into the form, then click Debug.
This will give you a snapshot of what exactly Facebook sees for that URL - the title, image, link, and much more (including the 'last scraped' date). To force Facebook to recrawl your page for updated information, click on the Scrape Again button.
Facebook will then recrawl your page, and you should see your updated data (like images and titles) being reflected in the shared preview!
To learn more about Facebook's Open Graph metatags, check out their official documentation.
Twitter has a similar tool in the Twitter Card Validator. Insert the URL of the post giving you the trouble and click Preview Card. This will automatically clear Twitter's cache and re-acquire the data from your page, showing the most up-to-date information based on your current twitter:card meta tags.
LinkedIn keeps the cached data from a shared post for a week from the first time the link is shared. Since LinkedIn doesn't have a dedicated share preview page like Twitter and Facebook, if you need to clear the sharing preview cache, we'll need to 'trick' LinkedIn into thinking that your page is a brand new page.
To do this, we're going to add an invented variable to your post's URL. So when you go to LinkedIn to share your URL, modify the URL slightly to add that invented variable. For example:
Post URL: http://www.domain.com
"New" Post URL: http://www.domain.com/?1
This will make LinkedIn think you are sharing a brand new page, and it force the metadata to be recollected by LinkedIn. Don't worry - this won't affect your webpage at all!
LinkedIn also uses the Open Graph metatags to determine what content to include in the shared preview of your post. You can learn more about the Open Graph tags in the official documentation.