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 ('88b8aec8555f077eee4116ebc8c9fcec', -1, 1369256600, 1369256600, '3210115a', -1, 0, 0)

Line : 187
File : sessions.php