Look for the original repository of your POS system. Check the "Issues" or "Pull Requests" tab. Often, other developers have already written the fix you need.

Check your config.php or .env file. Ensure the database name, host, and password match your local environment (XAMPP/WAMP) or your live server. PHP Version Incompatibility

Older POS source codes often use deprecated functions like mysql_connect (instead of mysqli ) or handle arrays in ways that PHP 8.x no longer supports.

A Point of Sale system handles sensitive transaction data. If you are modifying source code, never ignore these three things: