问题
Why isn't the Facebook debugger able to parse http://www.brandenburg-business-guide.de/ ? It reports 301 Circular redirect path detected. However, there is actually no redirection in place. Also apache's access.log reports no retrievals by facebook.
See https://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fwww.brandenburg-business-guide.de%2F and hit Debug button.
回答1:
The page does not contain any OpenGraph meta tags. Check out the documentation.
Facebook scraper expects the page to contain og:url meta tag which will serve as the canonical url OR link tag with rel="canonical". Since the document is missing both, Facebook cannot decide what is the canonical url, hence the circular redirect path error.
For a reference, try Goodreads debugging information.
Hope this helps.
来源：https://stackoverflow.com/questions/22226981/facebook-debugger-reports-circular-redirect-path-detected-301-on-certain-web