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 ('26c7cf40ad279c08d7a25d88a7cd2616', -1, 1398045611, 1398045611, '36d3bee8', 14, 0)

Line : 158
File : sessions.php