Is it safe to upgrade my PHP version?

The short answer

Yes, as long as you test the new version on a staging site first (a staging site is a private copy of your site for testing). In 2026 the version to aim for is PHP 8.3 or 8.4. PHP 7.4 and PHP 8.0 to 8.2 no longer receive security fixes, so staying on an old version is now the riskier choice, not the safe one.

What it means

PHP is the programming language WordPress is written in. Each PHP release gets a few years of bug fixes and security patches, then stops. Once a version is end of life, any new security hole found in it stays open on your server.

WordPress itself runs well on PHP 8.3 and 8.4, and newer PHP is noticeably faster, which is a free speed gain. The risk sits in plugins and themes. A plugin that was written years ago may use a function that PHP 8 removed. When that code runs, PHP stops with a fatal error and your visitors see a blank page or a message about a critical error. The fix is almost always to update or replace that one plugin, which is exactly what a staging test reveals before any customer sees it.

Common causes

• An abandoned plugin. One that has not had an update in a long time and still uses functions removed in PHP 8. This is the most common cause of a broken site after an upgrade.
• An old custom theme or child theme. Code written for your site years ago by a developer who has moved on.
• Custom snippets in functions.php or a must-use plugin that nobody remembers adding.
• Deprecation warnings being displayed. These are harmless notices, but if error display is switched on they print across the page and look like a crash.
• Assuming the plugin’s Tested up to line covers PHP. That line refers to the WordPress version, not the PHP version, so it is only a rough signal.

How to fix it

1. Find your current version. In WordPress go to Tools, then Site Health, then the Info tab, and open the Server section. It lists the PHP version in use.
2. Update everything first. Go to Plugins, then Installed Plugins, and update WordPress, every plugin and your theme. Click View details on each plugin and note the last updated date and the Tested up to line. Anything abandoned for a long time goes on a watch list. If the plugin’s page on wordpress.org states a required PHP version, note that too.
3. Create a staging copy. In the management console (Plesk with WP Toolkit), open WP Toolkit, find your site card and use Clone to create a staging copy. On other hosts use whatever staging feature or plugin is provided. The principle is host independent: test on a copy, never on live.
4. Change PHP on the staging copy only. In the console go to Websites & Domains, then PHP (PHP Settings) for the staging domain, and choose 8.3 or 8.4. If WP Toolkit offers a PHP compatibility check on the site card, run it as well. It flags plugins with known problems before you even load a page.
5. Turn on logging on staging. Open the staging site’s wp-config.php in File Manager and add define('WP_DEBUG', true); define('WP_DEBUG_LOG', true); define('WP_DEBUG_DISPLAY', false);. Errors now go quietly to wp-content/debug.log instead of onto the page.
6. Click through the whole site. Homepage, a few inner pages, search, a contact form, and for a store a complete test order through checkout. Then open the admin: edit a post, view orders, open each plugin’s settings page. Read debug.log afterwards. Fatal errors name the plugin file responsible.
7. Fix what broke. Update, replace or remove the offending plugin on staging and test again. If you cannot replace it, a developer can usually patch a small plugin in an hour or two, but a modern alternative is nearly always the better long-term answer.
8. Repeat on the live site. Take a backup, then go to Websites & Domains, then PHP for the live domain, and select the same version. Click through again. If anything is wrong, choosing the old version in the same screen puts it back in seconds.
9. Tidy up. Remove the debug lines from wp-config.php on both sites and delete the staging copy if you no longer need it.

On WP Alpha

Test the new version on a staging site first. On WP Alpha a staging site is one click in WP Toolkit inside the management console (Plesk with WP Toolkit), so there is no reason to experiment on your live site.

PHP 7.0 through 8.5 are all available and 8.3 or 8.4 is our recommendation. The version is set per site under Websites & Domains, then PHP, so your staging copy and your live site can run different versions while you test. Backups run every two hours and are kept 30 days, so if a problem only shows up later, a restore is queued from the console. If you are not comfortable doing the switch yourself, support is available 24/7 by live chat and ticket and can run the staging test with you.