Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5c968db5302df1.49577536", "HbeynBkmw6dwemj0xrMO6d9U8dpq0hym", "18.206.168.65", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: