Upgrade the current PHP 5.3 application to PHP 7.4

Hi there, we already have a working application written in core PHP that is running on PHP 5.3. We need to upgrade the source code to support PHP 7.4. The code was written in MySQLi Procedural method, hence you need to maintain the same method to avoid logic changes. The application includes frontend application and the admin portal. The code changes would need to be done to around 50 pages of the application. We can discuss more about the project after you bid.