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 ('b0d08e298a4a57e6f472df3dfe1a1498', -1, 1513292031, 1513292031, '3652519a', 42, 0, 0)

Line : 189
File : sessions.php