You need to install mbstring on your server. 

FIX ** for any one else that runs into it..

ENABLE: "Mbstring"

1. You can access EasyApache by going to the Software section of WHM and clicking on EasyApache. Command-line folks can just use /scripts/easyapache.

2. If you're asked to update, do so then come back to this screen. Updates often contain enhancements to allow EasyApache to support updated technologies.

3. On the first screen ("1. Profile"), select "Previously Saved Config (** DEFAULT **)" and then click on "Start customizing based on profile."

This setting will display your current settings throughout the rest of the EasyApache interface. This way you don't need to lookup what your current configuration is, you just change the items you want to have changed (e.g. adding mbstring support to PHP)

4. Continue clicking "Next" until you get to "5. Short Options List" then click "Exhaustive Options List" at the bottom of the page.

5. Under PHP, check the checkbox for "Mbstring" then click "Save and Build"

6. Follow any further on-screen instructions that appear.

oh yeah i seen you other post from another Josh from 2013. Thanks again Ross!

no problem

Just had the same issue when trying to enable Cache i was hit wit this error, going to apply will let you know if fixed. :) Thanks guys !!

Thanks Josh for taking the time to share that. It is much appreciated and im sure it will help others :) 

It worked Guys, Thanks...!!!

Great... Yes WHM is a wonderful thing :)