Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5c6d67cdc5dbe6.16183679", "pJiLAG7TtioVXK9LYcWL17hv99BLhMl0", "18.206.175.155", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: