Cannotupgradeandroidin-appsubscription.Error:"Somethingwentwrongonourend.Pleasetryagain."

Issue:

• Cannot upgrade current subscription to different subscription.
• Showing Error: "Something went wrong on our end. Please try again."

Description:

• Were using play billing library v3.0.3 and we handled subscription upgrade as code below.

BillingFlowParams purchaseParams = BillingFlowParams.newBuilder()
                    .setSkuDetails(skuDetails)
                    .setOldSku(oldSKU, oldPurchaseToken)
                    .setReplaceSkusProrationMode(IMMEDIATE_WITH_TIME_PRORATION)
                    .build();

• Things were as expected when we launched.
• Some users reported that they cannot upgrade their subscription.
• We tested upgrade and same error was encountered: "Something went wrong on our end. Please try again."
• Then we upgraded to play billing library v4.0.0 thinking it would solve our issue.

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();

• Same error is reported again: "Something went wrong on our end. Please try again."
• Also new play billing library v4.0.0 does not have method setOldSkuPurchaseId() in class SubscriptionUpdateParams.Builder but mentioned in developer docs

Error Screenshot Attached Below