mb_convert_encoding, undefined function while mbstring is enabled

Question

I have a server (Ubuntu 11.10 x64) running PHP 5.3.8 with Apache2 / MySQL. I'm currently working on a project where I'm required to do some specific character encoding, but I found out that none of the multibyte (mb_* functions) are working.

However, when I look in phpinfo(), I see that multibyte support is enabled.

I've tried things like apt-get install php5-mbstring, php-mbstring, php-multibyte, etc. etc. but none seem to work.

Can anyone point me in the right direction for this? Thanks in advance!

edit: Fixed it by recompiling PHP (this was my last resort, which I initially wanted to avoid)

./configure --enable-mbstring

The weird this is, phpinfo() already showed that it was enabled. I don't know why it didn't work before :/

what is the error message when you try any of the mb_* functions? — Emir Akaydın, Nov 25 '11 at 08:33
Web server configuration vs. CLI configuration? Where exactly do you see what? — deceze, Nov 25 '11 at 08:44
@EmirAkaydın - call to undefined function mb_substr or mb_convert_encoding. — Harold, Nov 25 '11 at 09:44
You solved my problem with your solution, so thanks a lot for that! :) — Pedro, Sep 16 '16 at 03:46
Do you have libmbfl installed? If so - it should be shown in `phpinfo()` output as "Multibyte string engine" under mbstring. — Narf, Nov 25 '11 at 08:52
Yeah I have that installed. However, I just noticed that the "Zend Multibyte Support" is disabled. Is there a way to enable this without having to recompile PHP? — Harold, Nov 25 '11 at 08:58
I don't think it has something to do with the mbstring extension. — Narf, Nov 25 '11 at 09:02

score 50 · Accepted Answer · answered Nov 01 '13 at 13:46

50

A lot of newer Linux servers do not have PHP Multibyte modules installed by default. A simple solution is often to install php-mbstring.

On Red Hat flavors (CentOS, Fedora, etc.) you can use yum install php-mbstring.

Make sure you restart your Apache server afterwards. Use service httpd restart on RH flavors.

answered Nov 01 '13 at 13:46

Lance Cleveland

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`sudo apt-get install php7.0-mbstring` and then `sudo service php7.0-fpm restart` did the trick for me. Thanks! – neilsimp1 Sep 02 '16 at 18:37
I had additionally edit the /etc/php/7.0/mods_available/mbstring.ini and remove the ; for the extension line. Suddently it started working for me :) – Maarten Kieft Oct 30 '16 at 12:40
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After installation need to run sudo service apache2 restart. – Baharuni Asif Jun 22 '20 at 14:07

score 7 · Answer 2 · edited Aug 27 '18 at 20:40

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In the case of your installation is php5.6 is similar to solution of neilsimp1:

Running sudo apt-get install php7.0-mbstring and then sudo service php7.0-fpm restart did the trick for me.

sudo apt-get install php5.6-mbstring

and then restart apache service

sudo service apache2 restart.

edited Aug 27 '18 at 20:40

Daniel

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answered Aug 27 '18 at 20:17

rpaillao

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score 2 · Answer 3 · answered Jul 02 '16 at 06:06

Sometimes people receiving this kind of error : Fatal error: Call to undefined function mb_convert_encoding() in /public_html/this/this.php at line 188. Normally this kind of errors comes in PHP Sites and PHP framework aswell.

It looks like PHP mbstring not installed on your server.

Solution :

In my case I have just uncomment ;extension=php_mbstring.dll in php.ini file and issue has been resolved.

Don't forget to restart apache server after uncomment ;extension=php_mbstring.dll

Code taken from this blog: http://chandreshrana.blogspot.in/2016/01/call-to-undefined-function.html

This was the working solution for me (using windows, IIS, php 7.4). Don't forget to restart IIS. — LAamanni, Jul 19 '21 at 09:00

HoldOffHunger · Answer 4 · 2021-12-29T19:31:59.240

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Check if MBString is Installed

You can know if it is actually installed or not with the -m (Show compiled in modules) arg...

php -m | grep mbstring

If installed, you will see mbstring as the output from the above, or blank if it is not installed.

Install MBString

If you have the newest PHP (PHP8 right now), you can install with...

apt-get install php-mbstring 
yum install php-mbstring

If you have PHP7, and you need an older MBString, then install with...

apt-get install php7.0-mbstring
yum install php7.0-mbstring

Restart the Server

Restart the server after install with this at your command line:

/etc/init.d/apache2 restart

Refer back to step 1 to check that MBString actually installed.

edited Dec 29 '21 at 19:31

answered Dec 29 '21 at 18:33

HoldOffHunger

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This is very system specific, and not very widely applicable; where does php70w-mbstring come from? Most people do not run PHP as an Apache module any longer, and if they do there's a good chance the old sysv init scripts aren't available; most systems use systemd now. – miken32 Dec 29 '21 at 19:21
Oops, that was actually a copy/paste error, thanks for catching, I meant to have [`php7.0-mbstring`](https://stackoverflow.com/a/35892829/2430549) there. – HoldOffHunger Dec 29 '21 at 19:32

mb_convert_encoding, undefined function while mbstring is enabled

edit: Fixed it by recompiling PHP (this was my last resort, which I initially wanted to avoid)

4 Answers4

Check if MBString is Installed

Install MBString

Restart the Server

Linked