Upgrade WordPress to PHP 8.3 Safely: Step-by-Step Guide

WordPress: Tools → Site Health → Info → Server shows your PHP version. Note your WordPress, theme and plugin versions too.

wp core version
php -v
wp plugin list --fields=name,status,version,update_version

Use your host’s one-click snapshot or a backup plugin, and keep a copy off the server. With WP-CLI you can also export the database:

wp db export before-php-upgrade.sql

A backup you have never restored is only a hope, so try restoring it on a staging copy.

For each plugin, open its WordPress.org page and check three fields:

• Last updated: no update in about two years usually means abandoned (rule of thumb).
• Tested up to: should match a recent WordPress version.
• Requires PHP: must not demand something older than 8.3.

Pay extra attention to login and security plugins and backup or database plugins, because a break there can lock you out or stop your backups. Also search each one in the Patchstack or Wordfence vulnerability database.

wp core update
wp plugin update --all
wp theme update --all

Delete plugins and themes you do not use. Replace anything abandoned with a maintained alternative before you touch PHP.

Most good hosts offer a one-click staging copy. If yours does not, use a subdomain clone. On the staging copy, switch PHP to 8.3 (or 8.4) and turn on logging by adding this to wp-config.php:

define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);

Then visit the homepage, a post, the login page, search, contact forms and (for stores) the cart and checkout. Errors go to wp-content/debug.log. Remove the debug lines when you are done.

• Shared hosting: pick PHP 8.3 or 8.4 in cPanel MultiPHP Manager, Plesk or your host’s dashboard. The switch also restarts PHP for your site.
• VPS: update packages, then restart PHP-FPM (or Apache with mod_php).
• Docker: use a fixed tag such as php:8.4.27-fpm and rebuild.

sudo systemctl restart php8.3-fpm

Do the switch at a quiet time of day, and keep the panel open so you can change back.

Check Tools → Site Health for the new version, then repeat your checks: login (including 2FA and social login), forms, checkout, scheduled backups. Read the PHP error log for new warnings. Finally, ask your host to confirm the PHP2Shell patch is installed, since the version label alone does not prove it.