phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO docttorrdiscluc_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('a6a340489256d26ddbae807d23ab2c66', -1, 1547894431, 1547894431, '22cbd574', -8, 0, 0)

Line : 190
File : sessions.php