title: Inconsistent - "The project id used to call the Google Play Developer API has not been linked in the Google Play Developer Console."
body: <p>So here's the thing - I have a node.js backend server for my Android App.  I am using the Google Play billing library, and using the backend to verify the purchase as google Docs recommend.</p>
  
  <p>Now, all the other answers out there regarding this error seem to refer to a consistent problem.  </p>
  
  <p>My backend SOMETIMES verifies, and SOMETIMES comes back with this as an error, indicating that in fact, my service account IS linked (as shows up in my consoles).</p>
  
  <p>I tried two different 3rd party libraries, and I have the same issue.  Sometimes one will respond with verification success, while the other will say my account is not linked.  Sometimes they are both negative, sometimes both positive.</p>
  
  <p>It seems inconsistent.</p>
  
  <pre><code>var platform = 'google';
          var payment = {
              receipt: purchaseToken, // always required  ... this is google play purchaseToken
              productId: subID,  // my subscription sku id
              packageName: 'com.xxxxxx', // my package name
              keyObject: key,  // my JSON file
              subscription: true, // optional, if google play subscription
  
          };
  
  
  
     var promise2 = iap.verifyPayment(platform, payment, function (error, response) {
          /* your code */
          if (error) {
              console.log('error with iap, ' , error);
              return true;
          } else {
              console.log('success with iap, response is: ', response);
              return true;
          }
      });
  </code></pre>
  
  <p>I also tried with a different library, got same results:</p>
  
  <pre><code>var receipt = {
              packageName: "com.xxxx",
              productId: subID,  // sku subscription id
              purchaseToken: purchaseToken // my purchase token
              };
  
              var promise = verifier.verifySub(receipt, function cb(err, response) {
                  if (err) {
                      console.log('within err, was there a response? : ', response); 
                  console.log('there was an error validating the subscription: ', err);
                  //console.log(err);
                  return true;
                  } else {
                  console.log('sucessfully validated the subscription');
                  // More Subscription info available in “response”
                  console.log('response is: ', response    );
                  return true;
                  }
                 });
  
  
  // return promises later.
  </code></pre>
  
  <p>Any else experience this issue?  </p>