To downgrade the PHP version to 7.3 on an EC2 instance running Ubuntu, you need to remove the current PHP version and install PHP 7.3. Here are the steps to achieve this:

Step-by-Step Guide

Connect to Your EC2 Instance

Connect to your EC2 instance using SSH:

ssh -i /path/to/your-key.pem ubuntu@your-ec2-instance-public-dns

Remove Current PHP Version

First, you need to remove the currently installed PHP version. You can list the installed PHP packages and remove them:

sudo apt list --installed | grep php

Then remove the listed PHP packages (e.g., php8.1):

sudo apt-get purge 'php*'

sudo apt-get autoremove

Add PHP 7.3 Repository

You need to add the repository that contains PHP 7.3. The ondrej/php repository is commonly used for this purpose:

sudo apt-get install software-properties-common

sudo add-apt-repository ppa:ondrej/php

sudo apt-get update

Install PHP 7.3

Now, install PHP 7.3 and the necessary extensions:

sudo apt-get install php7.3

sudo apt-get install php7.3-cli php7.3-fpm php7.3-mysql php7.3-xml php7.3-mbstring php7.3-curl php7.3-zip

Configure Apache or Nginx to Use PHP 7.3

If you are using Apache:

sudo a2enmod php7.3

sudo systemctl restart apache2

If you are using Nginx, you need to configure Nginx to use PHP 7.3 by editing the server block configuration file:

sudo nano /etc/nginx/sites-available/default

Update the fastcgi_pass directive to point to the PHP 7.3 FPM socket:

nginx

Copy code

location ~ \.php$ {

   include snippets/fastcgi-php.conf;

   fastcgi_pass unix:/var/run/php/php7.3-fpm.sock;

   fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;

   include fastcgi_params;

}

Save the file and restart Nginx:

sudo systemctl restart nginx

sudo systemctl restart php7.3-fpm

Verify PHP Version

To verify that PHP 7.3 is installed and configured correctly, you can check the PHP version:

php -v

You can also create a phpinfo() file to check the PHP version through your web server:

echo "<?php phpinfo(); ?>" | sudo tee /var/www/html/phpinfo.php

Navigate to http://your-ec2-instance-public-dns/phpinfo.php in your web browser and verify that PHP 7.3 is being used.