Symptom
https://amplify.nginx.com/docs/guide-installing-and-managing-nginx-amplify-agent.html
During installing NGINX Amplify agent, the error below
2017-11-20 16:17:33,280 [23305] supervisor ssl certificate found /etc/letsencrypt/live/.ac.jp/fullchain.pem
2017-11-20 16:17:33,280 [23305] supervisor could not read /etc/letsencrypt/live/.ac.jp/fullchain.pem (maybe permissions?)
2017-11-20 16:17:33,287 [23305] supervisor running /usr/sbin/nginx -t -c /etc/nginx/nginx.conf
How to fix
check this
% ls -aslrt
total 44
4 drwx------ 3 root root 4096 May 7 2016 live
4 drwx------ 3 root root 4096 May 7 2016 archive
4 drwx------ 4 root root 4096 Oct 14 2016 accounts
4 drwx------ 2 root root 4096 Oct 1 05:00 keys
4 drwxr-xr-x 2 root root 4096 Oct 1 05:00 csr
4 drwxr-xr-x 2 root root 4096 Oct 1 05:00 renewal
4 drwxr-xr-x 5 root root 4096 Nov 1 11:26 renewal-hooks
4 drwxr-xr-x 9 root root 4096 Nov 1 11:27 .
12 drwxr-xr-x. 156 root root 12288 Nov 20 10:18 ..
then do
sudo chgrp {username} live
sudo chown {username} live
sudo chgrp {username} archive
sudo chown {username} archive
sudo chgrp {username} accounts
sudo chown {username} accounts
sudo chgrp {username} keys
sudo chown {username} keys
cf.
https://www.digitalocean.com/community/questions/permissions-issue-after-installing-lets-encrypt