Question

Recently I downloaded codeIgniter 2.1.1.
I droped the CI files on my wamp on windows 7, After that simply I opened up firefox and type localhost and I saw this message “Disallowed Key Characters”
But, I do not have this problem with Chrome and Opera.

Answer 1

There is this code in system/core/Input.php on line 728:

<?php 
/**
    * Clean Keys
    *
    * This is a helper function. To prevent malicious users
    * from trying to exploit keys we make sure that keys are
    * only named with alpha-numeric text and a few other items.
    *
    * @access   private
    * @param    string
    * @return   string
    */
function _clean_input_keys($str)
{
    if ( ! preg_match("/^[a-z0-9:_\/-]+$/i", $str))
    {
        exit('Disallowed Key Characters.');
    }

    // Clean UTF-8 if supported
    if (UTF8_ENABLED === TRUE)
    {
        $str = $this->uni->clean_string($str);
    }

    return $str;
}
?>

It checks the keys in key=>value pairs eg: example.com?key=value if your key is not within the range of a-z0-9:_/- it will throw that error.

Change exit('Disallowed Key Characters.');

to exit('Disallowed Key Characters.'.$str); to give you an idea about what key is at fault. Remember this perhaps is checking cookies through $_REQUEST/$_COOKIE so its also a good idea to clear your cookies, perhaps from an older script or version on the same path.

hope it helps