title: Fixing DoExpressCheckout error 10422 in production
body: <p>In production, DoExpressCheckout is returning PayPal error 10422 'The customer must return to PayPal to select new funding sources'.</p>
  
  <p>What docs I've found from PayPal are limited (<a href="https://developer.paypal.com/webapps/developer/docs/classic/api/errorcodes/#id09C3F05600A" rel="nofollow">https://developer.paypal.com/webapps/developer/docs/classic/api/errorcodes/#id09C3F05600A</a>)</p>
  
  <blockquote>
    <p>Instruct the customer to use a different funding source. Offer the customer a quick link to restart the Express Checkout flow and redirect the customer back to PayPal.</p>
  </blockquote>
  
  <p>I'm trying to figure out what this means since I personally have no way of regenerating the error and so have no way of testing my code (and asking my exasperated customer to do a couple walkthrus while I sort out the kinks seems unreasonable).</p>
  
  <p>Does anyone know</p>
  
  <ul>
  <li>references for causes of this error?</li>
  <li>How to generate this error myself to walkthrough for customer experience?</li>
  <li>What redirect should be used? (the first paypal.com...?token= url or should I now be including PayerID?).</li>
  </ul>
  
  <p>All comments solicited.</p>