Updating the PHP version in WordPress: More security, better performance and fewer risks

Updating the PHP version in WordPress: More security, better performance and fewer risks

WordPress is largely based on the PHP programming language. When a visitor opens your website, PHP processes many central tasks in the background: posts are loaded from the database, themes are executed, plugins run, forms are processed and dynamic content is generated.

PHP can therefore be compared quite well to the engine of a WordPress website. If the PHP version is outdated, the website often runs more slowly, less securely and with lower compatibility for modern plugins and themes. An up-to-date PHP version is therefore one of the most important technical foundations for a stable and secure WordPress website.

Why the PHP version is important for WordPress

Every WordPress site uses PHP. Even if you do not write any code yourself, WordPress, themes and plugins constantly work with PHP. The PHP version used therefore directly influences how well your website works.

An up-to-date PHP version usually offers several advantages:

• Better security: Supported PHP versions receive bug fixes and security updates.
• Better performance: Modern PHP versions can process many requests more efficiently.
• Better compatibility: Current themes and plugins are often developed for newer PHP versions.
• Less technical legacy: Outdated functions are gradually replaced.
• Future readiness: Websites remain easier to maintain and update.

Old PHP versions may still work in some cases, but they are risky in the long term. If a PHP version is no longer officially supported, it no longer receives regular security updates. This can be particularly problematic for publicly accessible websites.

Current PHP versions and support status

PHP versions have a fixed lifecycle. A version first receives active support, later only security updates, and then reaches so-called End of Life. From this point onward, the version is no longer officially maintained. The official PHP website explains this distinction between active support, security support and end-of-life versions.

For WordPress websites, it is therefore not only important whether a PHP version still technically works. It is also important whether it is still maintained for security purposes and reliably supported by current plugins and themes.

PHP 8.x: Why an upgrade makes sense

Compared with older PHP versions, PHP 8.x brings many technical improvements. These include performance optimizations, more modern language features and a better foundation for current software development.

For WordPress, this means: if your website, theme and plugins are compatible, an up-to-date PHP version can help process pages faster and reduce technical problems caused by outdated functions.

The actual performance gain depends heavily on your website. A simple WordPress site with a current theme benefits differently than a complex WooCommerce shop with many plugins. Broad promises such as “always 30 percent faster” are therefore not serious. In many cases, however, the difference is noticeable, especially when switching from very old PHP versions to modern PHP 8.x versions.

Which PHP version should I use for WordPress?

The best PHP version is not automatically the very latest version, but the newest stable version that is fully supported by your website. WordPress itself states that WordPress can still run on older PHP versions, but points out that old versions have reached their official end of life and can cause security risks.

For production WordPress websites, a careful but current approach is therefore recommended:

• PHP 8.3 or 8.4: Often a good choice for current, well-maintained WordPress websites.
• PHP 8.2: May still work, but should be upgraded to a newer version in the medium term.
• PHP 8.1 and older: Increasingly problematic for production websites and should be avoided where possible.
• PHP 7.4 and older: No longer appropriate for modern WordPress websites.

Which version is available in cPanel at CURIAWEB may vary depending on the hosting environment, package and time. If in doubt, choose a stable PHP 8.x version supported by your website and test the website carefully after switching.

1. Create a full backup before switching

Before changing the PHP version, you should create a full backup of your website. This is especially important for production websites, online shops, member areas and websites with forms or booking functions.

A full backup should include:

• WordPress files: Core files, themes, plugins and uploads.
• Database: Posts, pages, settings, users, comments and plugin data.
• Configurations: Important settings, redirects or custom adjustments.

If a problem occurs after the PHP change, you can use a backup to restore the previous state.

2. Update WordPress, themes and plugins

Before switching to a newer PHP version, WordPress, your active theme and all plugins should be as up to date as possible. Old plugins or unmaintained themes are the most common cause of problems after a PHP upgrade.

Check in particular:

• Is WordPress itself up to date?
• Is the active theme up to date?
• Are all important plugins still maintained?
• Are there plugins with compatibility warnings?
• Has a plugin not been updated for years?
• Are there custom code changes in the theme?

If a plugin has not been maintained for a long time, you should be especially careful. Such plugins can trigger errors with modern PHP versions.

3. Check compatibility beforehand

For more complex websites, it can make sense to check compatibility before switching. Especially with WooCommerce shops, member areas, booking systems or heavily customized themes, you should not switch blindly.

Possible checks include:

• reading plugin documentation,
• checking theme documentation,
• reviewing developers’ support notes,
• using a staging environment,
• checking error logs,
• testing critical functions after switching.

A staging environment is particularly safe because you can test changes there without putting the live website at risk.

4. Change the PHP version in cPanel

At CURIAWEB, depending on your hosting package, you can conveniently manage the PHP version in cPanel. The exact name of the tool may vary slightly depending on the server environment. The area is often called Select PHP Version or similar.

Typical process:

1. Log in to your cPanel.
2. In the Software section, look for Select PHP Version or PHP management.
3. Select the desired stable PHP version, for example PHP 8.3 or PHP 8.4, if available.
4. Click Set as current or save the change.
5. Open your website in a new browser window.
6. Check the homepage, subpages, forms, shop functions and WordPress login.

After switching, the website should be tested immediately. Some errors only appear on specific subpages or during specific actions.

5. Check the website after switching

After changing PHP, you should not just briefly open the homepage. Test the most important functions of your website systematically.

Check in particular:

• Homepage: Does it load correctly?
• Subpages: Do important pages and landing pages work?
• Contact forms: Can forms be submitted?
• WordPress login: Can you still log in?
• Dashboard: Are there error messages in the backend?
• WooCommerce: Do cart, checkout and product pages work?
• Search function: Are results displayed correctly?
• Menus and widgets: Is the layout displayed correctly?
• Caching: Does the cache need to be cleared?

If everything works, you can keep the new PHP version. If errors occur, first switch back to the previous version and investigate the cause.

6. Typical errors after a PHP upgrade

After switching to a newer PHP version, various errors can occur. The cause is almost always outdated code from plugins, themes or custom adjustments.

Typical signs include:

• white screen or critical error,
• error messages in the frontend,
• error messages in the WordPress dashboard,
• forms not working,
• problems with shop functions,
• layout errors,
• plugins no longer loading,
• entries in the error log.

If an error occurs, you should not immediately change all settings. Proceed in a structured way: reset the PHP version, check the error log, update or temporarily deactivate plugins, and identify the affected theme or plugin.

7. Return to the previous PHP version

One advantage of PHP management in cPanel is that in many cases you can switch the version back. If your website does not work correctly after the change, first select the previous working PHP version.

After that, you should look for the cause:

• Which plugin is causing the error?
• Is the theme compatible with the new PHP version?
• Are updates available?
• Is an old plugin still maintained at all?
• Is there a modern alternative?

Returning to the old version should only be a temporary solution if that version is outdated. In the long term, incompatible plugins or themes should be updated or replaced.

8. PHP extensions and settings

In addition to the PHP version, PHP extensions and settings may also be relevant depending on the hosting environment. Some plugins require certain extensions, for example for image processing, encryption, ZIP files or international character sets.

Typical PHP extensions that may be relevant for WordPress projects include:

• mysqli or pdo_mysql: Connection to the database.
• curl: External HTTP requests, API connections and updates.
• gd or imagick: Image processing.
• zip: ZIP files and plugin/theme installations.
• mbstring: Processing strings and special characters.
• intl: Internationalization and formatting.
• openssl: Encryption and secure connections.

Only change PHP extensions if you know what they are needed for or if a specific error message points to them.

9. PHP memory limit, upload limit and execution time

In addition to the version, PHP settings also play a role. Certain limits can be relevant especially for larger WordPress websites, page builders, WooCommerce or import functions.

Important values are:

• memory_limit: How much memory a PHP process may use.
• upload_max_filesize: Maximum size of uploadable files.
• post_max_size: Maximum size of POST requests, for example for forms or uploads.
• max_execution_time: Maximum runtime of a PHP script.
• max_input_vars: Number of input variables that can be processed, relevant for large menus or complex settings.

Higher values do not solve every problem and should not be set blindly. However, they may be necessary for certain WordPress setups.

10. PHP and security

An outdated PHP version is a security risk because known vulnerabilities are no longer regularly fixed after official support ends. This does not mean that every old PHP website will be hacked immediately. It does mean, however, that the risk increases unnecessarily.

For a secure WordPress website, several things should work together:

• current PHP version,
• current WordPress version,
• current plugins and themes,
• strong passwords,
• regular backups,
• firewall and brute-force protection,
• clean file permissions,
• SSL certificate,
• monitoring of important errors.

PHP is therefore an important security component, but not the only one.

11. PHP and performance

A modern PHP version can process requests more efficiently. This can be noticeable especially on dynamic WordPress pages, WooCommerce, member areas or extensive plugins.

However, PHP alone is not enough for good performance. What matters is the interaction of:

• current PHP version,
• fast hosting,
• clean caching,
• optimized database,
• few unnecessary plugins,
• optimized images,
• lean theme,
• reduced JavaScript and CSS.

A PHP upgrade is therefore an important foundation, but it does not replace complete performance optimization.

12. SEO and Core Web Vitals

PHP is not a visible SEO factor like a page title or a heading. Nevertheless, the PHP version can be indirectly relevant for SEO. If a modern PHP version speeds up server processing, this can have a positive effect on loading time and user experience.

Particularly relevant are:

• Time to First Byte: How quickly the server delivers the first response.
• Largest Contentful Paint: How quickly the most important visible content loads.
• Interaction to Next Paint: How responsive the website remains during interactions.
• Stability: Error-free pages create trust and a better user experience.

Good technical foundations help search engines and visitors. However, a PHP upgrade alone does not guarantee better rankings.

13. GEO: Why up-to-date technology also matters for AI search systems

GEO, or Generative Engine Optimization, describes the optimization of content for AI-supported search and answer systems. This is not only about text, but also about technical reliability.

A website that loads quickly, is reliably accessible and does not generate server errors provides a better foundation for search engines, crawlers and AI systems. An outdated PHP version, on the other hand, can lead to errors, incompatibilities or slower processing.

For GEO, the following are particularly important:

• stable accessibility,
• clean technical foundation,
• up-to-date software,
• fast loading times,
• structured content,
• reliable internal linking,
• no unnecessary error pages.

14. When you should be cautious with a PHP upgrade

For most well-maintained WordPress websites, switching to a current PHP version makes sense. Nevertheless, there are situations where special caution is required.

Be especially careful with:

• very old themes,
• plugins without recent updates,
• custom programming,
• WooCommerce shops,
• membership sites,
• booking systems,
• learning platforms,
• websites with many business-critical forms,
• undocumented code adjustments.

In such cases, testing in a staging environment is particularly recommended.

Recommended approach

1. Check current PHP version: Check in cPanel or WordPress which version is active.
2. Create backup: Back up files and database.
3. Update WordPress: Bring core, theme and plugins up to date.
4. Check compatibility: Pay special attention to old or unmaintained plugins.
5. Change PHP version in cPanel: Select a current stable PHP 8.x version.
6. Test website completely: Check frontend, backend, forms, shop and important functions.
7. Clear cache: Clear WordPress, plugin and browser cache.
8. Check error logs: If problems occur, check the error logs.
9. Switch back if errors occur: Temporarily restore the previous version and fix the cause.
10. Modernize long term: Replace incompatible plugins or old themes.

Frequently asked questions about the PHP version in WordPress

What is PHP in WordPress?

PHP is the programming language used to run WordPress on the server. It processes themes, plugins, database queries and many dynamic functions of your website.

Why should I update PHP?

An up-to-date PHP version improves security, compatibility and often also the performance of your website. Old PHP versions eventually stop receiving official security updates.

Which PHP version is recommended for WordPress?

For modern WordPress websites, a current stable PHP 8.x version supported by your theme and plugins is recommended. PHP 8.3 or 8.4 are often sensible options, provided your website is compatible.

Can a PHP upgrade damage my website?

Yes, if an old plugin, theme or custom code is not compatible. That is why you should create a backup beforehand and test the website carefully after switching.

Can I switch back to the old PHP version in cPanel?

In many hosting environments, you can switch back to the previous available PHP version in cPanel. However, this should only be a temporary solution if the old version is outdated.

Does PHP 8 automatically make my website faster?

Not automatically, but modern PHP versions can process many requests more efficiently. The actual effect depends on the theme, plugins, caching, hosting and database.

What should I do if an error appears after switching?

First switch back to the previous working PHP version. Then check plugins, theme, error logs and possible updates. An outdated plugin is often the cause.

Should I replace old plugins because of PHP compatibility?

Yes, if a plugin is no longer maintained or does not work with current PHP versions. Outdated plugins are a security and maintenance risk.