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 ('8d9bfd8b9c8a0cf0167fa14a9b997f91', -1, 1506197396, 1506197396, '36e09ee8', 5, 0, 0)

Line : 187
File : sessions.php