On the last couple of EE upgrades I've received a PHP error regarding MB_ENABLED:

A PHP Error was encountered Severity: Notice

Message: Use of undefined constant MB_ENABLED - assumed 'MB_ENABLED'

Filename: libraries/Encrypt.php

Line Number: 367

This is repeated for each instance of MB_ENABLED in the system/codeigniter/system/libraries/Encrypt.php file.

If I wrap each instance of MB_ENABLED in single quotes then it resolves the issue but having to do this on each upgrade is a little annoying.

It seems to be mentioned on the EllisLab forums also but the solution is again to modify core files. Is this a bug? Has anyone encountered this issue in upgrading recently?

  • I just upgraded from 2.5.x to 2.8.1, and am getting the same errors. I changed line 47 of /system/codeigniter/system/core/Utf8.php to "AND $CFG->item('charset') == 'UTF-8' OR 'utf-8'" and that got rid of the errors. The client's server doesn't have iconv enabled and I don't see this in the EECMS system reqs. Also, the server passed the ee wizard tests. Is this an issue with EE or my server? May 18, 2014 at 19:26

3 Answers 3


I have never seen this. I'm guessing there is something in your environment that EE doesn't like.

I found a PyroCMS thread which mentions this error. That CMS is (was) build on CodeIgniter. It mentions in that thread that you need to have the iconv extension installed. This extension is enabled by default in recent versions of PHP, so that would likely make this an uncommon error.


Check your PHPinfo to see if this extension has been enabled.


I just got this error when using channel:form, enabling 'iconv extension' fixed the issue.


This has been a long standing bug where the constant just wasn't defined. It's finally squished in EE 2.9:

"Fixed a bug where MB_ENABLED was undefined"

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.