PHP Fatal error: Call to undefined function json_decode()

Question

Apache is logging PHP Fatal error: Call to undefined function json_decode(). After some googling, it seems this problem is a result of not having the latest version of php. Oddly, running php --version ouputs

PHP 5.5.1-2+debphp.org~precise+2 (cli) (built: Aug  6 2013 10:49:43) 
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2013 Zend Technologies
    with Zend OPcache v7.0.2-dev, Copyright (c) 1999-2013, by Zend Technologies
    with Xdebug v2.2.3, Copyright (c) 2002-2013, by Derick Rethans

Clearly showing that my php version is greater than 5.1.

Any ideas as to what could cause this, or the steps to take to find out?

EDIT: The result of a script echoing phpversion is 5.5.1-2+debphp.org~precise

EDIT: The result of phpinfo() is also PHP Version 5.5.1-2+debphp.org~precise+2

Furthermore, in the phpinfo(), it lists the module JSON and the module authors (Omar Kilani, Scott MacVicar).

Solution 1

Using Ubuntu?

Short answer:

sudo apt-get install php7.2-json

(or php7.1-json or php5-json depending on the PHP version you're running)

Then of course make sure you restart Apache:

sudo service apache2 restart

Or if you are using PHP-FPM:

sudo service php7.2-fpm restart

(Or php7.1-fpm or php5-fpm)

Explanation

Debian has removed the previous JSON extension as of PHP 5.5rc2 due to a license conflict.

The JSON license has a clause which states:

The Software shall be used for Good, not Evil.

This causes a problem with Free Software Foundation's definition of free software which states:

The freedom to run the program, for any purpose (freedom 0).

FSF goes on to specifically list the JSON license as nonfree.

Yes it seems a bit silly. Nevertheless Debian has removed the non-compliant JSON extension, and instead offered a replacement extension that is functionally equivalent.

To be clear: PHP itself has NOT removed JSON, it's still in master. This is a distro / package manager issue.

Rasmus makes it pretty clear:

We have not removed json and we will never release a version of php without json support built in. Any changes in 5.5 is due to whatever distro packaging you are using which we have no control over.

More details

http://iteration99.com/2013/php-json-licensing-and-php-5-5/

http://liorkaplan.wordpress.com/2013/06/01/bye-bye-non-free-php-json-extension/

https://bugs.php.net/bug.php?id=63520

http://philsturgeon.co.uk/blog/2013/08/fud-cracker-php-55-never-lost-json-support

Solution 2

With Ubuntu :

sudo apt-get install php5-json
sudo service php5-fpm restart

Solution 3

Solution for LAMP users:

apt-get install php5-json
service apache2 restart

Source

Solution 4

As a RHEL 8 user, this was fixed with:

yum install php-json

And then reloading nginx and php-fpm. So basically the json libraries where missing from the default php install.

This should also work on CENTOS 8.

Solution 5

If you're using phpbrew try to install json extension to fix error with undefined function json_decode():

phpbrew ext install json

View more solutions

Comments

[Orangepill]

Check the disable_functions ini directive to see if json_decode is in that list

[tcmitche]

Does the json module show up in your phpinfo() output?

[MirroredFate]

disable_functions = pcntl_alarm,pcntl_fork,pcntl_waitpid,pcntl_wait,pcntl_wifexi‌​ted,pcntl_wifstopped‌​,pcntl_wifsignaled,p‌​cntl_wexitstatus,pcn‌​tl_wtermsig,pcntl_ws‌​topsig,pcntl_signal,‌​pcntl_signal_dispatc‌​h,pcntl_ge\ t_last_error,pcntl_strerror,pcntl_sigprocmask,pcntl_sigwaiti‌​nfo,pcntl_sigtimedwa‌​it,pcntl_exec,pcntl_‌​getpriority,pcntl_se‌​tpriority,

[jgb]

Ubuntu 12.04 has a package: php-services-json. Maybe this helps...

[mario]

@jgb That's the PEAR package Services_Json. Which is also quite encompassing, parses a bit Javascript, not just JSON even. But there are other userland implementations directly reimplementing json_decode.

[MirroredFate]

I came back to mention that it appears as if 5.5.0 is fine with JSON, it is only 5.5.1 that breaks.

[Luis Lobo Borobia]

5.5.3 does not have it neither (Ubuntu 13.10)

[Pavel]

Don't forget to restart apache after installing json module with the command Chris mentioned.

[rickfoosusa]

If php-json were a dependency of php-common this would all go away...bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/12800‌​30 ...please vote if this was a problem for you.

[Jürgen A. Erhard]

Ever wonder who defines this "Evil" here? And you'd use software that may or may not allow the use you put it to? Me? I wouldn't.

[recursion.ninja]

Does anyone find it ironically "evil" that this software licensing exclusion cost me an hour of research time?

[xilef]

If a restart fails to solve the error, kill the apache2 processes and start: sudo pkill apache2; service apache2 start

[E Ciotti]

still didn't work, I had to remove and reinstall php5-fpm + extensions (ubuntu 14, PHP 5.5.9-1ubuntu4.5)

[JRam13]

I just spent a HOURS debugging my php code! Are you kidding me with this... FML

[gies0r]

Same in FreeBSD: Use pkg install php56-json

[emix]

Guzzle's json_decode is using php's json_decode with additional error check, so your answer is invalid

[Smit Patel]

What about apt-get install php7.2-json for 7.2. I tried this but still not working. Giving me error on laravel app php RuntimeException PHP's json extension is required to use Monolog's NormalizerFormatter