直到最新的Certbot更新，一切正常。自动更新机制会通过电子邮件向我发送状态报告。现在报告说：
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Cert not yet due for renewal
Plugins selected: Authenticator webroot, Installer None
Cert not yet due for renewal
Could not choose appropriate plugin for updaters: The nginx plugin is not working; there may be problems with your existing configuration.
The error was: NoInstallationError()
如果我运行certbot renew --dry-run，则没有错误，并且letencrypt.log会显示“没有续订失败”。
我从未更改过/etc/cron.d/certbot文件-到目前为止，它始终可以完美地工作。我应该关注这个NoInstallationError()吗？哪些Nginx插件不起作用？
这是certbot cron文件：
# /etc/cron.d/certbot: crontab entries for the certbot package
#
# Upstream recommends attempting renewal twice a day
#
# Eventually, this will be an opportunity to validate certificates
# haven't been revoked, etc. Renewal will only occur if expiration
# is within 30 days.
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
0 */12 * * * root test -x /usr/bin/certbot -a \! -d /run/systemd/system && perl -e 'sleep int(rand(43200))' && certbot -q renew