phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO elranchito_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('dad8c8002f6bb55eeeacecaf52638ab9', -1, 1455315335, 1455315335, '3692c950', 19, 0, 0)

Line : 172
File : sessions.php