How to resolve "Call to undefined function Composer\Json\json_decode()" in PHP?

Question

I am in a Linux Mint system. I have install Composer. I am trying to install Laravel 4 in my www folder. I used this command composer create-project laravel/laravel l4 --prefer-dist at first they said I had to install mcrypt. I went to the PHP site and they said I need to install mcrypt using these commands.

apt-get install php5-mcrypt
mv -i /etc/php5/conf.d/mcrypt.ini /etc/php5/mods-available/
php5enmod mcrypt
service apache2 restart

I have done them. Now when I try to install Laravel 4 they say

Fatal error: Call to undefined function Composer\Json\json_decode() in phar:///usr/local/bin/composer/src/Composer/Json/JsonFile.php on line 217

I don't know what to do now.

Answer 1

The JSON module for PHP is missing, try this:

apt-get install php5-json

Answer 2

PHP extension are loading from two files

1. /etc/php5/apache2/php.ini, which is used by Apache. enabled modules can be verified by creating a php file with phpinfo();. check json is present in the list. If not, install json using "sudo apt-get install php5-json" command and then restart apache.

2. /etc/php5/cli/php.ini used by PHP while running from command line. enabled modules can be verified by "php -m" command without quotes. In my case json is not present in that list. enabling json module in php.ini file by adding "extension=json.so" to php.ini file solved the issue.