Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5c6823ba9908e5.35093207", "r4KO5Ic6Z8iJJE9J5QH4007SFGPHCTfo", "34.207.152.62", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: