[php][Resolved] PHP Fatal error: Call to undefined function mb_internal_encoding()

Check error log and found this:

Step 1
Firstly, you need to check are you installed php extension mbstring() since it's the non-default extension. This means it is not enabled by default. For detail pls visit php official site:
http://php.net/manual/en/mbstring.installation.php

Whether have you installed mbstring() extension (package php-mbstring) or not, you can run the command :

sudo yum install php-mbstring

If you haven't installed that, yum would ask you download the php-mbstring package or not, then you press "y" to download, otherwise it would tell you that you have already installed and "Nothing to do".

Restart your http service. (if you are not using centOS , the command maybe different.)

Create a php file and contains these content to check your php config, run that file on your server:

<?php phpinfo(); ?>
<hr />
<?php get_loaded_extensions(); ?>

And then check is extension "mbstring" loaded. If it's loaded, you may able to see something like that:

Reference:
http://php.net/manual/en/mbstring.installation.php
http://stackoverflow.com/questions/478844/how-do-i-see-the-extensions-loaded-by-php
http://blog.csdn.net/Duffy_Ma/article/details/45767315