The function the error states is undefined is a PHP function – mb_convert_encoding(). According to my documentation the multi-byte library – to which this functions belongs – has been around for quite some time and is usually supplied as standard.

Could you ask your host if, for some reason, your php does not contain it? And, I suppose… if not then why not and can it be added?

Thanks for the quick reply.

The mb library does appear to be installed. After turning ON mbstring.encoding_translation in our PHP config (off by default), the error persists when saving a post.

I’ve forwarded your note to my server manager. Any other suggestions?

Is that all that is needed for multi-byte handling? I suppose it is a daft question to ask but you did reboot your server after the change I assume? Yes?

Yellow Swordfish said
According to my documentation the multi-byte library – to which this functions belongs – has been around for quite some time and is usually supplied as standard.

Supplied yes, but not installed by default.

FYI: We are no longer seeing the Fatal Error with SP Uploads and Upload Viewer plugins both activated. Yay!

Now, for the record—and anyone else encountering this issue—a few notes from my server manager…

“Checking the EasyApache configuration settings for PHP that is currently installed, it appears that Mbstring is not included. It’s not a default setting to include it (in other words, it needs to be chosen in the PHP configuration).”

and…

“When you do a recompile of Apache/PHP, there are many options preselected in this system. That one is listed. Just not pre-selected. You should tell him that we use the Cpanel/WHM system.”

Thanks again for pointing out the mbstring requirement!

Good news. You will be able to use Emoji’s now as well 😉 What a bonus!

Jim, thanks for that tip.

It was not too bad of a job to recompile Apache with MBstring applied, which fixed my problem. 

For anyone running WHM / cPanel on a self managed server here is quick compile options.

EasyApache 101:

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.

The cool thing about EasyApache is that it will ensure everything will work before attempting to apply it to your server. In the relatively rare event that something fails, your current configuration is restored and you will be prompted to allow us to investigate what happened so we can resolve the issue.

FidoSysop said
For anyone running WHM / cPanel on a self managed server…

Roger that, thanks for sharing the details!

glad its resolved…