Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5c6d6aa0055df1.14153055", "zzEFztIomeF9hXTYICo8B2vGy0qId8S9", "18.206.175.155", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: