It's a simple helper for keep working your code if the server don't have installed multibyte functions library

A PHP Error was encountered
Severity: Error
Message:  Call to undefined function mb_XXXXXX()

• Copy multibytes_helper.php into the application/helpers directory

• Edit application/config/autoload.php file and load multibytes helper

• mb_strtolower
• mb_strtoupper
• mb_strlen
• mb_substr
• mb_strpos

• Codeigniter installed

This is a very basic solution for keep running in production your software