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 ('9703c7495bcc4a1042ac87a0614205c2', -1, 1547894497, 1547894497, '22cbd574', -7, 0, 0)

Line : 190
File : sessions.php