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, session_admin) VALUES ('c26b150f4b2d57001502bd02e2cbb34e', -1, 1231439697, 1231439697, '26673f39', 1, 0, 0)

Line : 172
File : sessions.php