What are some common errors that may occur when transitioning from PHP 5.6 to PHP 7.4.3?

One common error when transitioning from PHP 5.6 to PHP 7.4.3 is the use of deprecated functions or features that are no longer supported in the newer version. To solve this, you need to update your code to use the recommended alternatives provided by PHP 7.4.3. Another common error is the change in syntax or behavior of certain functions, requiring adjustments to your code to ensure compatibility. Example of updating code to use recommended alternatives:

// PHP 5.6 code using deprecated mysql extension
$conn = mysql_connect('localhost', 'username', 'password');
mysql_select_db('database', $conn);

// Updated code for PHP 7.4.3 using mysqli extension
$conn = mysqli_connect('localhost', 'username', 'password', 'database');