phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('2c3334a856ad761ecb5f2621768e0c62', -1, 1467255905, 1467255905, '36a682b9', 0, 0, 0)

Line : 172
File : sessions.php