What are the common pitfalls when migrating PHP code from an older version to a newer version?

One common pitfall when migrating PHP code from an older version to a newer version is deprecated functions or features. To solve this issue, you need to update your code to use the recommended alternatives or newer syntax provided in the newer PHP version.

// Deprecated function in PHP 7.4
$oldVar = mysql_real_escape_string($input);

// Updated code using mysqli_real_escape_string in PHP 7.4
$newVar = mysqli_real_escape_string($connection, $input);