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 ('131f76ae9d58351526f1a90c1e299acc', -1, 1397885438, 1397885438, '6b16258f', 10, 0)

Line : 158
File : sessions.php