Topic on Manual talk:Upgrading

If you are using php-fpm on your wikimedia site, you should restart this service after running php update.php as it caches the php files. If you do not restart php-fpm, you will get errors loading your wikimedia site as the old code tries to use the new database.

The command is:

systemctl restart php-fpm

This is relevant on CentOS (Stream) installations, for example.

The default opcache options for php-fpm automatically reloads php files when they're modified. If you've changed opcache configuration to not check for updates unless you restart/reload php-fpm that's a particularity of your installation that you should be aware of, like any customizations.