phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO mex2mex_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('79e877b0b4d16bd7b5511922b6f0bcbc', -1, 1406213095, 1406213095, '36514b45', 7, 0)

Line : 170
File : sessions.php