How to Change PHP Version & Settings

PHP is a widely used scripting language for web development, and different applications may require different PHP versions or settings to function properly. Whether you need to upgrade for security reasons, downgrade for compatibility, or modify settings for performance, this guide will show you how to change your PHP version and customize settings on different platforms.

---

Why Change PHP Version?

Changing the PHP version can be necessary for several reasons:

• Application Compatibility: Some websites and applications require a specific PHP version.

• Security Updates: Newer PHP versions include important security patches.

• Performance Optimization: Later PHP versions improve performance and reduce resource usage.

• Feature Support: Some functions and libraries are only available in newer versions of PHP.

---

How to Check Your Current PHP Version

Before making changes, check the current PHP version running on your server.

Check PHP Version via Command Line

If you have SSH access, run the following command:

php -v

This will display the installed PHP version.

Check PHP Version via cPanel

1. Log in to cPanel.

2. Navigate to Software > Select PHP Version.

3. Your current PHP version will be displayed at the top of the page.

Check PHP Version via a PHP Script

1. Create a new file called phpinfo.php.

2. Add the following code:

   <?php
   phpinfo();
   ?>

3. Upload the file to your website’s root directory.

4. Visit https://yourdomain.com/phpinfo.php in your browser.

---

How to Change PHP Version

Change PHP Version in cPanel

1. Log in to cPanel.

2. Go to Select PHP Version under the Software section.

3. Use the dropdown menu to choose your desired PHP version.

4. Click Set as Current to apply the change.

5. If needed, enable or disable PHP extensions.

Change PHP Version in Plesk

1. Log in to Plesk.

2. Navigate to Websites & Domains > PHP Settings.

3. Use the dropdown menu to select a different PHP version.

4. Click Apply or OK to save changes.

Change PHP Version Using .htaccess (Apache Servers)

If your server allows .htaccess overrides, add this line:

AddHandler application/x-httpd-php81 .php

Replace php81 with your desired PHP version.

Change PHP Version via Command Line (Linux)

For VPS or dedicated servers:

1. List available PHP versions:

   update-alternatives --list php

2. Change PHP version:

   sudo update-alternatives --set php /usr/bin/php8.1

3. Verify the change:

   php -v

---

How to Modify PHP Settings

Certain applications may require modifications to PHP settings like memory limit, max execution time, and file upload size.

Modify PHP Settings via cPanel

1. Log in to cPanel.

2. Go to Select PHP Version > Options.

3. Adjust settings such as:

   • memory_limit

   • upload_max_filesize

   • post_max_size

   • max_execution_time

4. Save changes.

Modify PHP Settings via php.ini

For servers with direct access to PHP configuration files:

1. Locate the php.ini file:

   find /etc -name php.ini

2. Edit it using a text editor:

   sudo nano /etc/php/8.1/apache2/php.ini

3. Modify values, for example:

   memory_limit = 256M
   max_execution_time = 300
   upload_max_filesize = 64M

4. Save and restart the web server:

   sudo systemctl restart apache2

Modify PHP Settings via .htaccess

If you do not have access to php.ini, modify settings via .htaccess:

php_value memory_limit 256M
php_value max_execution_time 300
php_value upload_max_filesize 64M

Save the file and check if the changes take effect.

Modify PHP Settings via CLI

For CLI applications:

php -d memory_limit=256M script.php

---

Troubleshooting PHP Version Issues

"500 Internal Server Error" After Changing PHP Version

• Ensure that required PHP extensions are enabled.

• Check the error log (/var/log/apache2/error.log or /var/log/nginx/error.log).

• Try switching back to a previous PHP version to see if the issue resolves.

"php.ini Changes Not Taking Effect"

• Restart Apache or Nginx:

  sudo systemctl restart apache2

  sudo systemctl restart nginx

• Check for multiple php.ini files using:

  php --ini

• Verify changes with phpinfo().

"Extensions Not Loading"

• Enable necessary PHP extensions in cPanel > Select PHP Version.

• Install missing extensions via CLI:

  sudo apt install php8.1-mbstring

• Restart PHP services after installing extensions.

---

Conclusion

Changing PHP versions and modifying settings is essential for compatibility, security, and performance. Whether using cPanel, Plesk, CLI, or .htaccess, following the correct steps ensures a smooth transition. Regularly updating to supported PHP versions and optimizing settings helps keep your applications running efficiently.