supervisorでgunicornを起動できない

前提・実現したいこと

gunicornとnginxを使ったwebアプリケーションのWEBサーバーの構築をしています。
supervisorでgunicornを起動させたいのですが、上手くいきません。

発生している問題・エラーメッセージ

supervisorctl start app

を実行すると

app: ERROR (no such process)

と表示され、/etc/supervisord/conf.d/app.confの内容を変更して

supervisorctl reread

を実行すると

No config updates to processes

と表示されてしまいます。
恐らく**/etc/supervisord/conf.d/app.conf**が上手く読み込めていないようなのですが、対応の仕方がわからず困り果てております。

どなたかご教示頂けませんでしょうか？
このような場で質問をするのは初めてのため、不足情報がありましたら補足いたしますのでお知らせください。

該当のソースコード

/etc/supervisord/conf.d/app.conf

[program:app]
directory=/home/ec2-user/app_web
command=/home/ec2-user/.local/bin/gunicorn webapp:app --config /home/ec2-user/app_web/guniconf.py
numprocs=1
autostart=true
autorestart=true
user=ec2-user
redirect_stderr=true
startsecs=5
exitcodes=0,1

/etc/supervisord/supervisord.conf
（一部抜粋）

[unix_http_server]
file=/tmp/supervisor.sock   ; the path to the socket file
;chmod=0700                 ; socket file mode (default 0700)
;chown=nobody:nogroup       ; socket file uid:gid owner
;username=user              ; default is no username (open server)
;password=123               ; default is no password (open server)

[inet_http_server]         ; inet (TCP) server disabled by default
port=127.0.0.1:9001        ; ip_address:port specifier, *:port for all iface
;username=user              ; default is no username (open server)
;password=123               ; default is no password (open server)

[supervisord]
logfile=/var/log/supervisord.log ; main log file; default $CWD/supervisord.log
logfile_maxbytes=50MB        ; max main logfile bytes b4 rotation; default 50MB
logfile_backups=10           ; # of main logfile backups; 0 means none, default 10
loglevel=info                ; log level; default info; others: debug,warn,trace
pidfile=/var/run/supervisord.pid ; supervisord pidfile; default supervisord.pid
nodaemon=false               ; start in foreground if true; default false
minfds=1024                  ; min. avail startup file descriptors; default 1024
minprocs=200                 ; min. avail process descriptors;default 200
;umask=022                   ; process file creation umask; default 022
;user=supervisord            ; setuid to this UNIX account at startup; recommended if root
;identifier=supervisor       ; supervisord identifier, default is 'supervisor'
;directory=/tmp              ; default is not to cd during start
;nocleanup=true              ; don't clean up tempfiles at start; default false
;childlogdir=/tmp            ; 'AUTO' child log dir, default $TEMP
;environment=KEY="value"     ; key value pairs to add to environment
;strip_ansi=false            ; strip ansi escape codes in logs; def. false

[rpcinterface:supervisor]
supervisor.rpcinterface_factory = supervisor.rpcinterface:make_main_rpcinterface

[supervisorctl]
serverurl=unix:///tmp/supervisor.sock ; use a unix:// URL  for a unix socket
serverurl=http://127.0.0.1:9001 ; use an http:// url to specify an inet socket
;username=chris              ; should be same as in [*_http_server] if set
;password=123                ; should be same as in [*_http_server] if set
;prompt=mysupervisor         ; cmd line prompt (default "supervisor")
;history_file=~/.sc_history  ; use readline history if available

;[group:thegroupname]
;programs=progname1,progname2  ; each refers to 'x' in [program:x] definitions
;priority=999                  ; the relative start priority (default 999)

; The [include] section can just contain the "files" setting.  This
; setting can list multiple files (separated by whitespace or
; newlines).  It can also contain wildcards.  The filenames are
; interpreted as relative to this file.  Included files *cannot*
; include files themselves.

;[include]
;files = ect/supervisord/conf.d/*.conf
files = /etc/supervisord/conf.d/*.conf