title: Google OAuth 2.0 refresh token 400 Bad Request only for some users
body: <p>I'm using OAuth 2.0 to access Gmail accounts, only for some accounts i receive "<strong>NO Invalid credentials</strong>" when trying to login through the SASL XOAUTH2 mechanism.
  <br />For those accounts if i try to refresh the access token Google returns me <strong>400 Bad Request</strong> and an html response:<br /></p>
  
  <pre><code>&lt;HTML&gt;
  &lt;HEAD&gt;
  &lt;TITLE&gt;Error processing OAuth 2 request&lt;/TITLE&gt;
  &lt;/HEAD&gt;
  &lt;BODY BGCOLOR="#FFFFFF" TEXT="#000000"&gt;
  &lt;H1&gt;Error processing OAuth 2 request&lt;/H1&gt;
  &lt;H2&gt;Error 400&lt;/H2&gt;
  &lt;/BODY&gt;
  &lt;/HTML&gt;
  </code></pre>
  
  <p>Suggestions? I have read on Google Developers site that to receive support by Google i have to write here.</p>
  
  <p><strong>EDIT:</strong>
  This is the raw request from Fiddler, the same request for other accounts works good</p>
  
  <pre><code>POST https://accounts.google.com/o/oauth2/token HTTP/1.1
  Content-Type: application/x-www-form-urlencoded
  Host: accounts.google.com
  Content-Length: 175
  Expect: 100-continue
  Connection: Keep-Alive
  
  refresh_token=1%2FNyVRzman0nPK9cis4ctiigyBvl1yfsPxb6REXXXXXXXX&amp;client_id=6206XXXXXXXX.apps.googleusercontent.com&amp;client_secret=h4-q_wigfzlwGkGkXXXXXXXX&amp;grant_type=refresh_token
  </code></pre>