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 ('7c8ea0c045c4ac0b5f17a15a7a51bc2f', -1, 1283510685, 1283510685, '266bbf6e', 1, 0)

Line : 170
File : sessions.php