Facebook Error Message: Requires valid next URL.

June 16th, 2010 • 1 comment facebook, php, snippets
Tags: api error, invalid parameter

Let me start with asking you a few questions!

1. Are you having issues with the Facebook API?
2. Are you constantly getting the error message “API Error Code: 100 API Error Description: Invalid parameter Error Message: Requires valid next URL.“?
3. Are you using the latest official Facebook PHP class?
4. Are you redirecting using the PHP header() function?

Well,  I might have a solution for you. When calling the function getLoginUrl in the Facebook PHP class, the function will return a HTML encoded string. When outputing this string to your browser, it is rendered/decoded by a browser and this will convert all “safe” charachters to their textual equivalent.  This makes that “&” becomes “&” and “%20″ becomes ” “.

However, when using the header() function in PHP, this url will not be rendered/decoded and you are basically sending out a garbled request.

Original

getLoginUrl($params);
header('Location:' . $url);

Solution:

getLoginUrl($params);
$url = str_replace('&','&',urldecode($url));
header('Location:' . $url);