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 ('c7956fbf4b3376549cdc79b3d77ce6b7', -1, 1414229264, 1414229264, '36c4a8ec', 33, 0)

Line : 315
File : sessions.php