PHP 7.2 Initial DCE and SCCP optimizations Parameter Type Widening In PHP 7.1 you would get: Allow trailing commas everywhere Object typehint Deprecate unquoted strings extra headers array arg for mail() and mb_send_mail() 'webmaster@example.com', 'Reply-To' => 'webmaster@example.com', 'X-Mailer' => 'PHP/' . phpversion() ]; mail($to, $subject, $message, $headers); ]]> Argon2i added to password_hash() 2048, 'time_cost' => 10, 'threads' => 2 ]; echo password_hash("rasmuslerdorf", PASSWORD_ARGON2I, $options); ]]> Add Sodium Crypto Library Things that may break your code mcrypt extension has been removed __autoload() deprecated, use spl_autoload_register() create_function() deprecated, use anonymous functions each() deprecated, use foreach() read_exif_data() deprecated, use exif_read_data() Full details are at: And for extension authors: