phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('0abd0f0db6442e8466a2f4989f9ef675', -1, 1513292262, 1513292262, '3652519a', -7, 0, 0)

Line : 189
File : sessions.php