Upgrading the PHP version of a WordPress website is one of the most effective ways to improve performance, security, and long-term compatibility. Since WordPress, themes, and plugins all rely on PHP to run, an outdated version can slow down the site or expose it to avoidable risks. A safe upgrade requires preparation, testing, and a careful rollout rather than simply changing a server setting.
TLDR: A WordPress PHP upgrade should begin with a full backup, compatibility checks, and updates to WordPress core, themes, and plugins. The safest method is to test the new PHP version on a staging site before applying it to the live website. After the upgrade, the site owner should review key pages, forms, checkout flows, and error logs to confirm everything works correctly.
Why Upgrading PHP Matters
PHP is the programming language that powers WordPress behind the scenes. Each newer PHP version typically includes speed improvements, security patches, and better memory handling. When a WordPress site runs on an unsupported PHP version, it may become vulnerable to attacks and may also stop working properly with modern plugins or themes.
Performance is another major reason to upgrade. Newer PHP versions can process requests faster, which may reduce page load times and improve the experience for visitors. For business websites, online stores, and membership platforms, even small performance gains can make a noticeable difference.
However, the upgrade should not be rushed. Some older plugins, custom code, or abandoned themes may not be compatible with the latest PHP version. That is why a structured process is essential.
Step 1: Check the Current PHP Version
Before making any changes, the site owner should identify the version currently running. This can usually be found inside the WordPress admin area by going to Tools > Site Health > Info > Server. The PHP version should be listed there.
Many hosting control panels also display PHP information. Depending on the host, this may appear under sections such as PHP Manager, MultiPHP Manager, Server Settings, or Advanced Tools.
If the site is running an outdated version, such as PHP 7.4 or older, an upgrade should be planned. WordPress generally recommends using a modern supported PHP version, but the exact best choice depends on host support and plugin compatibility.
Step 2: Create a Complete Backup
A full backup is the most important safety step. The backup should include both the website files and the database. WordPress files contain themes, plugins, uploads, and core files, while the database stores posts, pages, settings, users, orders, and other dynamic content.
The site owner can create a backup using a trusted backup plugin, the hosting control panel, or a managed hosting backup tool. Ideally, the backup should be stored off the server, such as in cloud storage or downloaded to a secure local location.
- Back up files: themes, plugins, media uploads, and WordPress core files.
- Back up the database: posts, pages, comments, users, and settings.
- Verify the backup: confirm that the backup completed successfully before continuing.
Step 3: Update WordPress, Themes, and Plugins
Before changing PHP versions, the site should be fully updated. Developers usually add compatibility improvements for newer PHP versions in recent plugin and theme releases. Running old software increases the chance of errors after the upgrade.
The site owner should update WordPress core first, then update plugins and themes. If the website uses a premium theme or paid plugins, license keys should be active so that updates can be downloaded properly.
It is also wise to remove unused plugins and themes. Inactive or abandoned extensions can create unnecessary security and compatibility risks.
Step 4: Review Plugin and Theme Compatibility
Not every plugin or theme supports every PHP version. The site owner should check each important plugin’s documentation, changelog, or WordPress.org listing for PHP compatibility information. Special attention should be given to plugins that handle payments, memberships, forms, caching, security, and custom fields.
If a plugin has not been updated for several years, it may not be safe to rely on it. In that case, the site owner should look for a maintained alternative before upgrading PHP.
Custom themes and custom plugins deserve extra care. If the website uses custom code, a developer should review it for deprecated PHP functions or syntax that newer PHP versions no longer support.
Step 5: Use a Staging Site
A staging site is a private copy of the live website used for testing. This is the safest place to test a PHP upgrade because visitors will not see errors if something breaks. Many managed WordPress hosts offer one-click staging tools. If not, a staging environment can be created manually or with a migration plugin.
Once the staging copy is ready, the site owner can switch its PHP version to the target version through the hosting panel. After that, the staging website should be tested thoroughly.
Important items to test include:
- Homepage, blog posts, service pages, and landing pages
- Contact forms, newsletter forms, and search features
- Login, registration, and password reset pages
- WooCommerce carts, checkout pages, and payment gateways
- Membership dashboards, booking systems, or learning portals
- Admin dashboard functions, including editing and publishing content
Step 6: Enable Debugging During Testing
WordPress debugging can help reveal hidden problems. On a staging site, debugging may be enabled by editing the wp-config.php file. When active, it can log warnings, notices, and fatal errors that may not be visible on the front end.
The site owner or developer should inspect the debug log after testing the staging site. Even if the website appears normal, the log may show compatibility issues that should be fixed before the live upgrade.
Debugging should generally not be left visible on a live production site, because public error messages can expose sensitive information.
Step 7: Upgrade PHP on the Live Site
After the staging site passes testing, the live site can be upgraded. The site owner should choose a low-traffic time for the change, such as early morning or a scheduled maintenance window. This reduces the impact if quick troubleshooting is needed.
The exact process depends on the hosting provider. In most cases, the PHP version can be changed from the hosting control panel. Some hosts allow PHP selection per website, while others require support assistance.
After selecting the new PHP version, the change may take effect immediately or after a short delay. The site owner should clear any server cache, WordPress cache, and CDN cache to make sure the site loads fresh files.
Step 8: Test the Live Website After the Upgrade
Once the live site is running the new PHP version, testing should be repeated. The site owner should visit key pages, submit forms, test checkout if applicable, and log in to the admin dashboard. If the website has analytics or uptime monitoring, those tools should also be watched closely for unusual changes.
Server error logs should be checked after the upgrade. Fatal errors, repeated warnings, or unusual resource usage can indicate a compatibility issue. If problems appear, the backup and the previous PHP version provide recovery options.
What to Do If the Site Breaks
If the site shows a critical error, blank screen, broken layout, or failed checkout after the upgrade, the first step is to stay calm and revert the PHP version if possible. Most hosting panels allow the previous PHP version to be restored quickly.
Once the site is stable again, the issue should be investigated on staging. Common causes include outdated plugins, old themes, custom code, or missing PHP extensions. A developer may be needed if the problem involves custom functionality.
The site owner should avoid repeatedly changing settings without a plan. A careful rollback, diagnosis, and retest process is safer than guessing.
Best Practices for Future PHP Upgrades
- Maintain regular backups so recovery is always possible.
- Keep WordPress updated to reduce compatibility issues.
- Remove abandoned plugins and replace unsupported tools.
- Use staging before major technical changes.
- Monitor hosting notices about PHP end-of-life dates.
PHP upgrades are not a one-time task. As older versions reach end of life, hosting providers and software developers move forward. A well-maintained WordPress site should be reviewed regularly so upgrades can happen smoothly instead of during an emergency.
FAQ
What PHP version should a WordPress site use?
A WordPress site should use a modern, supported PHP version recommended by WordPress and available from the hosting provider. The best choice depends on plugin, theme, and custom code compatibility.
Can upgrading PHP break a WordPress website?
Yes, it can happen if the site uses outdated plugins, old themes, or incompatible custom code. This is why backups and staging tests are strongly recommended.
Is a backup necessary before upgrading PHP?
Yes. A complete backup allows the site owner to restore the website if something goes wrong during or after the upgrade.
Should plugins be updated before changing PHP?
Yes. Updated plugins are more likely to support newer PHP versions and are generally safer to run.
How long does a PHP upgrade take?
The actual PHP switch may take only a few minutes, but safe preparation and testing can take longer. The process should not be rushed, especially for business-critical websites.
Does upgrading PHP improve site speed?
Often, yes. Newer PHP versions usually process code more efficiently, which can improve WordPress performance when the rest of the site is properly optimized.
