Will Updating PHP Break My Site? What Really Happens
Will updating PHP break my site? Usually not, and when it does it's fixable. What breaks, how to test safely, and how to roll back in minutes.
It's the question every website owner asks right before they need to click 'update': will updating PHP break my site? The honest answer is usually no, and when something does break, it is almost always one old plugin or theme, not your whole website. Since the PHP2Shell security flaw in October 2026, staying on an old PHP version is the bigger risk by far. Here is what actually changes when you update, what can break, how to test it safely first, and how to undo it in minutes if you need to.
What actually changes when PHP updates
PHP is the language your website's server runs. WordPress, WooCommerce, Laravel and most business websites are written in it. Each new version runs faster and closes security holes, but it also removes old functions that were marked as outdated years earlier. Your website's own code is fine as long as it doesn't rely on those removed pieces. Modern, maintained software doesn't. Code written ten years ago and never updated sometimes does.
What can break, and why
- ✦Old plugins that haven't been updated in years. This is the cause in the vast majority of cases.
- ✦Old or custom themes, especially ones bought once and never updated.
- ✦Custom code added by a developer long ago, such as snippets in functions.php.
- ✦Very old WordPress versions. WordPress itself runs well on current PHP, but only if WordPress is kept up to date too.
What it looks like when something breaks: a white screen, a 'critical error' message, a page section missing, or a form or checkout that stops working. Your content, products, orders and images are not deleted. They are still in the database; the page just can't display until the incompatible piece is fixed or removed.
Why staying on old PHP is the bigger risk
PHP versions older than 8.2 no longer get regular security updates. When the PHP2Shell flaw was announced on 21 October 2026, the fixed versions were 8.5.12, 8.4.27, 8.3.36 and 8.2.35. Older versions only got emergency fixes as source code, which almost no shared hosting will install for you. A site on old PHP is exposed to flaws that will never be fixed for it, and automated attacks scan for exactly those sites.
How to update PHP safely, step by step
- 1Take a full backup of files and database, and check that you can download it.
- 2Update WordPress core, every plugin and every theme first. Most compatibility problems disappear at this step.
- 3Delete plugins and themes you don't use. Inactive code can still break or be attacked.
- 4If your host offers a staging site, copy your site there and switch the staging copy to the new PHP version first.
- 5Click through the pages that matter: home, contact form, checkout or booking, and anything with custom features.
- 6If staging works, switch the live site to the same PHP version (8.3 or 8.4 for most sites today).
- 7Check the live site again on a phone and a laptop, and submit a test enquiry or order.
If something breaks: rolling back takes minutes
On almost every host you can switch PHP back to the previous version from the same menu you used to update it, such as 'Select PHP Version' or 'MultiPHP Manager' in cPanel, or the PHP setting in your managed hosting dashboard. The site works again straight away. Then find the culprit: deactivate plugins one at a time on staging until the error disappears, and replace or update that one plugin. Don't stay on the old version for long; treat the rollback as a few days' breathing room, not a fix.
When to get help
If your site is built on an old theme, has custom code nobody remembers, or takes payments, it is worth having a developer do the update. We do this every week: back up, update on a staging copy, fix whatever breaks, switch the live site, and test everything that earns you money. Most sites are done within a day. If the site turns out to be too old to update safely, we tell you plainly and quote a rebuild on a modern setup instead.
Not sure where your site stands? Send us the link and we'll check your PHP version, plugins and theme for free, and tell you exactly what an update would involve.
Need your website patched and secured?
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Before you ask
Questions about this one
No. Your pages, posts, products and orders live in the database and are not touched by a PHP update. If something breaks, it is how the site displays, and switching PHP back restores it straight away.
PHP 8.3 or 8.4 for most WordPress sites today, on a patched release (8.3.36, 8.4.27 or later). Versions older than 8.2 no longer get regular security updates.
In WordPress, go to Tools, Site Health, Info, and open Server. In cPanel, open 'Select PHP Version' or 'MultiPHP Manager'. On managed hosting, look for a PHP setting in the dashboard.
Yes. We back up, update on a staging copy, fix anything that breaks, then switch the live site and test it. Send us the link for a free check first.
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