phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO start_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('439069e25be8194c1946b6cd1df5b68d', -1, 1427756352, 1427756352, '36c50fc4', -1, 0)

Line : 158
File : sessions.php