Uncaught Error: Call to undefined function NOW()

Use $date = date();, NOW() is for MySQL.

Read the documentation for more information about date().

Here is an example (from this documentation) :

$today = date("F j, Y, g:i a");                   // March 10, 2001, 5:16 pm
$today = date("m.d.y");                           // 03.10.01
$today = date("j, n, Y");                         // 10, 3, 2001
$today = date("Ymd");                             // 20010310
$today = date('h-i-s, j-m-y, it is w Day');       // 05-16-18, 10-03-01, 1631 1618 6 Satpm01
$today = date('\i\t \i\s \t\h\e jS \d\a\y.');     // It is the 10th day (10ème jour du mois).
$today = date("D M j G:i:s T Y");                 // Sat Mar 10 17:16:18 MST 2001
$today = date('H:m:s \m \e\s\t\ \l\e\ \m\o\i\s'); // 17:03:18 m est le mois
$today = date("H:i:s");                           // 17:16:18
$today = date("Y-m-d H:i:s");                     // 2001-03-10 17:16:18 (le format DATETIME de MySQL)

To get the current date in datetime format, you can do :

$date = new Datetime();

Read the documentation for more information about datetime.

If you are in MySQL, you can use NOW() like this for example :

$sql = "INSERT INTO mytable (current_date) VALUE (NOW())";

And again, here is the documentation if you want to know more about NOW().

Hope it helps !