Solusi Codeigniter 2.x Error Common 257

A PHP Error was encountered
Severity: Notice
Message: Only variable references should be returned by reference
Filename: core/Common.php
Line Number: 257

Buka File : /system/core/Common.php
Pada Baris 257

return $_config[0] =& $config; 

ganti dengan

$_config[0] =& $config; 
return $_config[0];