title: Using a guid in google anlytics userId field
body: <p>Has anyone experience of setting the <code>userId</code> field in the tracking code as a <code>guid</code>?</p>
  
  <p>I am trying but events are not being tracked. I tried with a random, shorter string and it worked. The <a href="https://developers.google.com/analytics/devguides/collection/analyticsjs/field-reference#userId" rel="nofollow">google api documentation</a> states there is no maxlength. I'm guessing there must be.</p>
  
  <pre><code>//var userId = 'dvdvddvdv'; // works
  var userId = 'bee302e50ccc42f9a17ea5bb01125968'; // not works
  ga('create', {
              trackingId: 'UA-XXXX-1',
              cookieDomain: 'auto',
              userId: userId
          });
  </code></pre>
  
  <p><strong>Update</strong></p>
  
  <p><a href="https://code.google.com/p/analytics-issues/issues/detail?id=923" rel="nofollow">Confirmed on Google support to be a bug</a></p>