cakephp error when saving data

Question

I have a cakephp console application with the following code :

$this->Message->save(
    [ "Message" =>
        [
            "delivery_class" => null,
            "user_id" => $user_id,
            "messages_class" => self::MESSAGE_CLASS,
            "project_id" => $project_id,
            "text" => $__MessageTmp,
            "attachment_id" => null,
            "opened" => 0,
            "is_deleted" => 0,
            "created_on" => $__NOW,
            "updated_on" => $__NOW,
        ],
    ]
)

This code is printing the error of PDO::quote and the SQL query error near

'2016-12-20')

I think there is some wrong data formatting in the query but can't figure out why.