Verify return code: 21 (unable to verify the first certificate) Lets encrypt Apache to Nginx with crontab issue

Solution 1:

Found the answer here: https://community.letsencrypt.org/t/cannot-verify-domain-with-openssl/11545

You'll have to refer to fullchain.pem in your webserver configuration, in stead of cert.pem.

Get to nginx virtual server config

sudo nano /etc/nginx/sites-enabled/default

I changed this line

ssl_certificate /etc/letsencrypt/live/www.goeasysmile.com/cert.pem;

ssl_certificate /etc/letsencrypt/live/www.goeasysmile.com/fullchain.pem;

This was preventing me from sharing pretty links via facebook metatag info like og:image. Now it can yay!