Today my good old paypal ipn script failed to post back to www.paypal.com/cgi-bin/webscr in order to verify a payment notification as usual. Strange! They said:

HTTP/1.1 301 Moved Permanently

It seems they are expecting the payment parameter as a GET query now,while I sent data by POST until now. It worked fine until yesterday. Urgh, it's about money, so I've to check this out promptly.

Well, my script is too old and too simple to handle 301 automatically, but fortunately it's clever enough to report the error.