If you have Facebook Like and Share buttons enabled on your storefront (as described in "How to Add Facebook Like and Share Buttons to a Product"), you may occasionally find that one of the buttons fails to appear on a page.
This is caused by Facebook failing to clear their cache for this product page. The remedy for this is as follows:
- Enter http://developers.facebook.com/tools/debug in your browser window (or follow the link). This will take you to the Facebook URL Debugger.
- Enter the full address for the product (or other page) where the button is failing to display.
- Click Debug.
This forces Facebook to refresh the Like / Share cache data for this page. Once done, your button should start to appear again on this page. Unfortunately, Facebook does not provide a method to clear the cache for an entire domain, so individual pages must be cleared as the problem occurs.