问题:

How long is Facebook caching the sharing thumbnails? I've added a custom thumbnail for my page using:

<meta property="og:image" content="/path/to/my/image" />

But on pages my previous image is displayed => it is cached somewhere on FB servers.

Any ideas how to flush that cache or how long does it take once FB loads a new image?

回答1:

Check the page with Facebook URL Linter, it seems to reload the thumbnails images in the cache.

http://developers.facebook.com/tools/lint

回答2:

Facebook images are cached on a different servers on a different location. According to what I have read, it will take 3 to 5 years before the image is refresh/deleted permanently after the last time it was accessed. So if the image keeps being accessed it won't be flushed. Not until you give up on shutting down your site.