I was just about to create a post about this.   We have been using the v3 API since some weeks ago and all of sudden it stopped working.   We have investigating our code and came to the conclusion the issue is in the API side.   We can successfully make the authorization code request and receive the code.   Then we are able to exchange the code for an access token.   We are also able to use the refresh token in order to get a new access/refresh token.   The problem is that when we use the access_token to perform API requests, like:   curl -X GET \ 'https://api.cc.email/v3/contacts?status=all&email=someperson%40domain.com&include_count=false&includ...' \ -H 'Content-Type: application/json' \ -H 'Authorization: Bearer INSERT_SOME_VALID_RECENT_ACCESS_TOKEN_HERE' \ -H 'Cache-Control: no-cache' \ -H 'Accept: application/json'   We always get the response:   {"error_key":"unauthorized","error_message":"Unauthorized"} ... View more