Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5c9692867f04e8.96217025", "SR7mGJQF4wzLaIJskREvUYvLCmFfRNvo", "18.206.168.65", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: