title: Cannot upgrade android in-app subscription. Error: "Something went wrong on our end. Please try again."
body: <h2>Issue:</h2>
  <ul>
  <li>Cannot upgrade current subscription to different subscription.</li>
  <li>Showing Error: &quot;Something went wrong on our end. Please try again.&quot;</li>
  </ul>
  <h2>Description:</h2>
  <ul>
  <li>Were using <code>play billing library v3.0.3</code> and we handled subscription upgrade as code below.</li>
  </ul>
  <pre class="lang-java prettyprint-override"><code>BillingFlowParams purchaseParams = BillingFlowParams.newBuilder()
                      .setSkuDetails(skuDetails)
                      .setOldSku(oldSKU, oldPurchaseToken)
                      .setReplaceSkusProrationMode(IMMEDIATE_WITH_TIME_PRORATION)
                      .build();
  </code></pre>
  <ul>
  <li>Things were as expected when we launched.</li>
  <li>Some users reported that they cannot upgrade their subscription.</li>
  <li>We tested upgrade and same error was encountered: <em>&quot;Something went wrong on our end. Please try again.&quot;</em></li>
  <li><strong>Then we upgraded to <code>play billing library v4.0.0</code></strong> thinking it would solve our issue.</li>
  </ul>
  <pre class="lang-java prettyprint-override"><code>BillingFlowParams billingFlowParams = BillingFlowParams.newBuilder()
          .setSubscriptionUpdateParams(SubscriptionUpdateParams.newBuilder()
              .setOldSkuPurchaseToken(oldPurchaseToken)
              .setOldSkuPurchaseId(oldSKU) // This method is not available in lib[4.0.0] but mentioned in docs
              .setReplaceSkusProrationMode(IMMEDIATE_WITH_TIME_PRORATION))
          .setSkuDetails(skuDetails)
          .build();
  </code></pre>
  <ul>
  <li>Same error is reported again: <em>&quot;Something went wrong on our end. Please try again.&quot;</em></li>
  <li><em>Also new <code>play billing library v4.0.0</code> does not have method setOldSkuPurchaseId() in class  SubscriptionUpdateParams.Builder but mentioned in <a href="https://developer.android.com/google/play/billing/subscriptions#proration" rel="noreferrer">developer docs</a></em></li>
  </ul>
  <p><strong>Error Screenshot Attached Below</strong></p>
  <p><img src="https://i.stack.imgur.com/yNxkC.jpg" alt="screenshot" /></p>