I am getting the following error while trying to install Let's Encrypt SSL on my website:

Saving debug log to /var/log/letsencrypt/letsencrypt.log

Obtaining a new certificate

Performing the following challenges:

http-01 challenge for linuxbuz.com

http-01 challenge for www.linuxbuz.com

Using the webroot path /var/www/html for all unmatched domains.

Waiting for verification...

Cleaning up challenges

Failed authorization procedure. linuxbuz.com (http-01): urn:acme:error:unauthorized :: The client lacks sufficient authorization :: Invalid response from http://linuxbuz.com/.well-known/acme-challenge/pYpAC6kT25C0itcTNKd8hwb_0VaoPxJVIkVg5_xn-N4 [77.111.240.95]: 403

IMPORTANT NOTES:

 - The following errors were reported by the server:

   Domain: linuxbuz.com

   Type:   unauthorized

   Detail: Invalid response from

   http://linuxbuz.com/.well-known/acme-challenge/pYpAC6kT25C0itcTNKd8hwb_0VaoPxJVIkVg5_xn-N4

   [77.111.240.95]: 403