Fatal error about JsonSerializable

Question

While I have php 5.5.3 and Joomla 3.1.5, I get this error:

Fatal error: Interface 'JsonSerializable' not found in /var/www/joomla/libraries/joomla/registry/registry.php on line 22

This is the output of php --version:

PHP 5.5.3-1ubuntu2 (cli) (built: Oct  9 2013 14:49:24) 
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2013 Zend Technologies
    with Zend OPcache v7.0.3-dev, Copyright (c) 1999-2013, by Zend Technologies

Answer 1

Are you using Ubuntu 13.10? If so, try installing the php5-json package. I guess it is perhaps new to 13.10 .

I have it and PHP v5.5.3 working fine so far. See this link for someone's blog (not mine) about installing Joomla with Ubuntu 13.10 (which has PHP v5.5.3).

Answer 2

If you have a look at the Technical requirements for Joomla 3.x, you will see that the minimum is PHP 5.3 and the recommended is 5.4.

So I would strongly recommend that you go back to PHP 5.4 as I believe there are a few known issues with PHP 5.5 and above.

Answer 3

This was an issue with Debian not including the interface in their PHP version due to some ridiculous legal arguments. This will be fixed in the next version of Joomla (3.3.1) see https://github.com/joomla/joomla-cms/commit/dac8a08d30ed7580b546544c4b9a1da19c3fd7de

Answer 4

apt-get install php5-json enable or add json extension on the php.ini file

extension=json.so