phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO elranchito_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('6977e3347f4ccc785d93a58d0df8a439', -1, 1475285205, 1475285205, '36e2eeb2', 19, 0, 0)

Line : 172
File : sessions.php