interesting facebook status code 500 error on linux server, PHP

index.h开发者_运维知识库tml is working on facebook debug.

index.php is not working on facebook debug.

this site is reachable, but facebook is not reaching. what is the problem?

Though it works in the browser, when I try to load your site from the command-line using CURL, it responds with an 500 Internal Server Error and no page. It seems that your site blows up whenever the client doesn't send the Accept-Language header. This header is optional, so you probably shouldn't do that.

Your page is returning a 500 error to Facebook's crawler. Also when I check it manually I get the same problem, as Jeremy reported.

Do you have any logic in your PHP which checks the user agent header and does different things on different user agents?

The Facebook crawler presents as facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)