Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5d1271351ec7c3.36058947", "IUYn3Q6OJonxP10ffSMgdmCzg31zHirr", "34.204.36.101", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: