Error: Failed authorization procedure. www.example.com (http-01): urn:ietf:params:acme:error:unauthorized :: The client lacks sufficient authorization :: Invalid response from…

There might redirect rules in effect. Try putting this in your .htaccess or vhost file:

RewriteCond %{REQUEST_URI} !^\.well-known/(.*)$

• Debian 10.8
• certbot 0.31

• Install certbot
• Install certbot via manual method
• Certbot download certificates only