CI Error - Disallowed Key Characters

Error   Disallowed Key Characters

function _clean_input_keys($str)
 {
  if ( ! preg_match("/^[a-z0-9:_\/\-\.|]+$/i", $str)) 
  //if ( ! preg_match("/^[a-z0-9:_\/-]+$/i", $str))
  {
  
   
   exit('Disallowed Key Characters.' . ' : ' . $str);  

   //exit('Disallowed Key Characters.');


  }