phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('f160bf8d98ee44c538b2170a87a7ec5f', -1, 1436042414, 1436042414, '36a29d88', -4, 0, 0)

Line : 189
File : sessions.php