Fixed: “The URI you submitted has disallowed characters.” CodeIgniter (CI) Error

In Codeigniter 2.1.x version if you find “The URI you submitted has disallowed characters.” message then you can solve it easily by following the below step.
Follow the following way to fix this error. (assuming codeigniter 2.1.x)
In Codeigniter application/config/config.php file. Go to the line 129

$config['permitted_uri_chars'] = 'a-z 0-9~%.:_-';

(As a security measure you are STRONGLY encouraged to restrict URLs to as few characters as possible.By default only these are allowed: a-z 0-9~%.:_-) change this code by 
If you want to allow the comma(,) in your url

$config['permitted_uri_chars'] = 'a-z 0-9~%.:_,\-'; 

Leave blank to allow all characters -- but only if you are insane.
After changes the code, save the file and refresh your browser.
DO NOT CHANGE THIS UNLESS YOU FULLY UNDERSTAND THE REPERCUSSIONS!!