When a PHP upgrade becomes necessary
PHP versions have a defined support lifecycle. Once a branch reaches end of life, the PHP project no longer provides fixes for newly discovered security problems or bugs in that branch.
As of 1 October 2026, PHP 8.1 is already unsupported, having reached end of life on 31 December 2025. PHP 8.0 and PHP 7.4 have been unsupported for longer. PHP 8.2 remains within security-only support until 31 December 2026, so sites using it should already be planning their next move rather than waiting for support to expire.
The correct target version is not simply the highest number available in a hosting control panel. The site's WordPress version, theme, plugins and custom PHP code need to support the target environment. That is particularly important on older sites that have accumulated custom functions or components that are no longer maintained.
Why updating PHP can break an older WordPress site
Changing PHP alters the runtime used to execute WordPress, plugin, theme and custom code. Code written for an older branch can depend on behaviour that has since been deprecated, changed or removed.
The resulting failure is not always a completely blank website. A site can appear normal while a particular function fails, such as an administration screen, scheduled process, form or checkout path. That is why testing only the homepage after changing the PHP selector is not enough.
Compatibility problems commonly sit outside WordPress core. An old theme, abandoned plugin or bespoke integration may contain the code that needs attention. Updating PHP without first establishing those dependencies turns a planned maintenance task into live fault-finding.
If a PHP change has already caused a live failure, our emergency website fix service is designed for broken-site incidents.
How we carry out a PHP version upgrade
Our PHP upgrade service is built around testing before the production environment changes. We first review the site's themes and plugins for compatibility issues and identify custom code that may need attention.
- Compatibility audit: review the WordPress installation and relevant code against the proposed PHP version.
- Staging test: reproduce and test the change away from the public website first.
- Code fixes: correct identified incompatibilities that prevent the site working properly on the newer PHP branch.
- Functional checks: test important site functions rather than relying only on the absence of an error message.
- Controlled switchover: move the production site to the tested PHP version with a rollback plan available.
The service includes a zero-downtime switchover and rollback planning. The objective is to make the version change controlled and reversible rather than experimenting on the live website.
Choosing the right PHP version
PHP currently maintains several supported branches, and their status is not identical. PHP 8.2 is receiving critical security support until 31 December 2026. PHP 8.3 has security support until 31 December 2027. PHP 8.4 remains in active support until 31 December 2026 and then security support until the end of 2028. PHP 8.5 is also a current supported branch.
That does not mean every existing WordPress site should be moved directly to PHP 8.5 without testing. A supported version still has to be compatible with the application running on it. For an older business website, the sensible target is a currently supported PHP branch that the site's maintained software and required integrations can run on correctly.
This also gives a clearer upgrade path for future maintenance. Remaining on an obsolete branch because one abandoned plugin requires it simply moves the problem forward. Where practical, the dependency itself should be updated, replaced or corrected.
PHP upgrade price and ongoing maintenance
The one-off PHP Upgrade Service is £399. It includes the compatibility audit, staging test, code fixes for identified incompatibilities, production switchover and rollback plan.
If the website has broader maintenance problems, a PHP upgrade can also be a useful point to review unsupported plugins, old themes and hosting configuration. Those are separate issues, but they often explain why a routine runtime update has been postponed for years.
Our WordPress maintenance services handle ongoing software updates, while hosting support covers server-level matters without requiring you to move to a new host.