If you are developing new site, you have probably locked it through htpasswd. When you are done with og meta data, you might want to check it with https://developers.facebook.com/tools/debug/sharing/ – but facebook won’t be able to access your content, because you can’t give it your password.

You need to update your htaccess, from

AuthUserFile /.htpasswd
AuthName Disbait
AuthType Basic
Require valid-user
satisfy any
deny from all
allow from 127.0.0.1

to

SetEnvIfNoCase User-Agent "^facebookexternalhit" facebook
SetEnvIfNoCase User-Agent "Facebot" facebook
SetEnvIfNoCase User-Agent "Twitterbot" twitter

AuthUserFile /.htpasswd
AuthName "Restricted Access"
AuthType Basic
Require valid-user
satisfy any
deny from all
allow from 127.0.0.1
allow from env=facebook
allow from env=twitter

Credit coderwall.com/p/8y7t1q/whitelist-facebook-twitter-to-test-your-open-graph-and-twitter-card-implementations