What are the common pitfalls in maintaining older PHP scripts on newer versions?

One common pitfall in maintaining older PHP scripts on newer versions is deprecated functions and features. To solve this issue, you should update your code to use current PHP functions and features. Another pitfall is incompatible syntax changes, which can be resolved by updating the syntax to match the current PHP version.

// Deprecated function example
// Old code using deprecated function
$oldVar = mysql_real_escape_string($input);

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