Yahoo! now allows you to use either PHP 4 or PHP 5 to run PHP code on your site. You can run only one version at a time, but you can switch anytime.

(If you signed up for your Small Business account before August 2010 and have not already switched to PHP 5, you are running PHP 4.)

We recommend that you run the latest version of PHP available. Although we have reinforced our system to ensure PHP 4 runs safely, PHP 5 is generally considered more secure and best supports modern applications and scripts.

To switch your account to run a different version of PHP:

1. Visit the Create & Update tab of your Web Hosting Control Panel.
2. Click to open the Other Site Building Tools module.
3. Click PHP Version to visit the PHP Version page.
4. You'll see two buttons, with your current PHP version selected. To switch to the other supported version, click that version's button.
5. Click Update to save your changes. The PHP version associated with your account will be changed automatically.

Be sure to monitor your site carefully after you make any changes to ensure that your site continues to function as expected. Learn about the effects of switching.