Facebook caches preview images the first time you post or share a coupon on your Facebook timeline.

Why?

While this can be somewhat annoying at first, Facebook does it to keep the sharing between users running smoothly. You can imagine the speed impact if Facebook spent time re-loading the same image each time it was shared from person to person. To avoid this, Facebook saves one copy of the image (related to the URL) and allows everyone to reference the cached version. This cache is stored for quite a while - to let the sharing continue - and you may find an overlap if you're looking to share the same URL six, nine or even twelve months down the road.

How to fix it?

To get around this, you'll need to reset the Facebook image cache using the following steps:

• Visit Facebook's debugging URL here: https://developers.facebook.com/tools/debug
• In the box, enter the URL of the coupon you wish to refresh.
• Click the "Debug" buttton.
• This prompts a manual scan of the URL, forcing an image update across the board.
• Go ahead and try posting the coupon again. This time, you'll see the new thumbnail instead of the old.

That's it - nothing to it!