PHP Versions and Configuration

PHP is the scripting language behind most websites and CMS like WordPress, Joomla or Drupal. This overview shows you the current PHP versions, their differences and how to configure them on your server.

Note: Detailed installation guides can be found in the articles in the left navigation.

Current PHP Versions

Why is the right PHP version important?

• Security: Old versions no longer receive security updates – your server becomes vulnerable
• Performance: Each new PHP version is faster. PHP 8.3 is up to 30% faster than PHP 7.4
• Compatibility: Outdated CMS versions don't run on new PHP – both must be current
• Features: New versions bring new functions and better error handling

Switching PHP Versions

On VPS/Root Server (Ubuntu/Debian)

# Show available PHP versions
sudo apt search php | grep -E "^php[0-9]+\.[0-9]+"

# Install new version (example: PHP 8.3)
sudo apt install php8.3 php8.3-cli php8.3-fpm php8.3-mysql php8.3-xml php8.3-mbstring php8.3-curl php8.3-zip -y

# Disable old version
sudo a2dismod php8.1  # For Apache
sudo a2enmod php8.3

# Restart web server
sudo systemctl restart apache2  # Apache
sudo systemctl restart nginx    # Nginx (with PHP-FPM)

On Webspace (Plesk)

1. Log in to Plesk
2. Go to Websites & Domains → PHP Settings
3. Select the desired PHP version from the dropdown menu
4. Click OK
5. The change takes effect immediately

Important PHP Configuration Values (php.ini)

PHP-FPM – The Performance Booster

PHP-FPM (FastCGI Process Manager) processes PHP requests significantly faster than the old mod_php. Instead of starting a new process for each request, FPM keeps a pool of running processes ready.

# Install PHP-FPM
sudo apt install php8.3-fpm -y

# Adjust pool configuration
sudo nano /etc/php/8.3/fpm/pool.d/www.conf

# Important settings:
pm = dynamic
pm.max_children = 20
pm.start_servers = 4
pm.min_spare_servers = 2
pm.max_spare_servers = 8
pm.max_requests = 500

# Restart after changes
sudo systemctl restart php8.3-fpm

Enforce PHP Version for Specific Website

Apache (via .htaccess)

# Set PHP 8.3 via .htaccess
AddHandler application/x-httpd-php83 .php

Nginx (via server block)

location ~ \.php$ {
    fastcgi_pass unix:/var/run/php/php8.3-fpm.sock;
}

Common Problems

Website shows white page after PHP update:

• Check if all required PHP extensions are installed (php -m)
• Check the error log: /var/log/php*-fpm.log or /var/log/apache2/error.log
• Turn on display_errors = On for troubleshooting

WordPress recommends outdated PHP version:

• WordPress itself runs on PHP 8.3 – the warning usually comes from old plugins or themes
• Update all plugins and themes
• Use a PHP compatibility plugin to find incompatible extensions

Detailed installation and configuration guides can be found in the articles in the left navigation.

Related guides

• Set up webspace
• Change nameservers – domain won't connect
• DNS not working / propagation
• Set up SSL correctly
• SPF, DKIM & DMARC (email)
• Email with your domain
• Make website faster
• Domain & DNS hub

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