let's encryptの更新

Question

let's encryptの更新作業をしているのですが、以下のエラーが発生してしまい
何が原因なのかご教示頂けないでしょうか
恐れ入りますが宜しくお願い致します

bitnami@ipxx:~$ sudo /usr/bin/certbot-auto renew --force-renew
Saving debug log to /var/log/letsencrypt/letsencrypt.log

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No renewals were attempted.

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bitnami@ipxx:~$ sudo cat /var/log/letsencrypt/letsencrypt.log
2019-09-17 07:14:30,974:DEBUG:certbot.main:certbot version: 0.38.0
2019-09-17 07:14:30,974:DEBUG:certbot.main:Arguments: ['--force-renew']
2019-09-17 07:14:30,974:DEBUG:certbot.main:Discovered plugins: PluginsRegistry(PluginEntryPoint#apache,PluginEntryPoint#manual,PluginEntryPoint#nginx,PluginEntryPoint#null,PluginEntryPoint#standalone,PluginEntryPoint#webroot)
2019-09-17 07:14:30,992:DEBUG:certbot.log:Root logging level set at 20
2019-09-17 07:14:30,993:INFO:certbot.log:Saving debug log to /var/log/letsencrypt/letsencrypt.log
2019-09-17 07:14:30,994:DEBUG:certbot.renewal:no renewal failures