phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('01c1cb783ba9fd8b3651e7c4e33e0b21', -1, 1417245754, 1417245754, '365159b6', -9, 0, 0)

Line : 187
File : sessions.php