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) VALUES ('df04a9da5e9cb01984ff4b9bd7a88344', -1, 1406520773, 1406520773, '36e2947a', 11, 0)

Line : 315
File : sessions.php