Another day another bug (or just weird behavior) in Facebook platform.

When calling $facebook->require_login() from anywhere else then a canvas page it is caught in an endless loop.

I was going crazy over this for few days. The big problem was that conditions under which this error occurs distinguish between IE and FireFox.


In short ... the solution is ... you have to carry Facebook signature variables (stored in $_GET) with you all the time.

$fbsig_vars = "";
$i=0;
foreach($_GET as $key => $value) {
 if (strpos($key,"fb_sig")!==false) {
    if ($i!=0) $fbsig_vars.= "&";
    $fbsig_vars.= "$key=$value";
    $i=1;
 }
}