I am developing a Flutter application where I need to integrate Paytm for payments. I have encountered issues with both the flutter_upi_india package and directly launching Paytm via URL schemes (paytm://). Here are the specifics of the problem:

Problem Description:

Using flutter_upi_india Package:

When attempting UPI payments using the flutter_upi_india package, transactions fail consistently across all payments apps (e.g., Paytm, PhonePe).
Direct URL Launch (url_launcher):

Trying to initiate payments by launching Paytm using url_launcher with the paytm:// URL scheme also results in failures.

import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';

class PaymentScreen extends StatelessWidget {
  final String paytmQrCode = "paytmqr2810050501011uduvuiplds0@paytm&pn=Paytm%20Merchant&paytmqr=2810050501011UDUVUIPLDS0"; // Replace with actual Paytm QR code
  final String transactionRefId = "txn123456789"; // Replace with a unique transaction reference ID
  final String transactionNote = "Payment for Order"; // Replace with transaction note
  final String amount = "100.00"; // Replace with the transaction amount in string format
  final String currency = "INR"; // Replace with the currency code

  void initiatePayment() async {
    // Constructing the Paytm QR URI
    Uri uri = Uri.parse(
        "paytm://wallet/pay?mId=paytm&pa=$paytmQrCode&tid=$transactionRefId&tn=$transactionNote&am=$amount&cu=$currency");

    if (await canLaunch(uri.toString())) {
      await launch(uri.toString());
    } else {
      throw 'Could not launch $uri';
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Pay via Paytm'),
      ),
      body: Center(
        child: ElevatedButton(
          onPressed: () {
            initiatePayment();
          },
          child: Text('Pay with Paytm'),
        ),
      ),
    );
  }
}


Expected Outcome:

I expect the app to launch Paytm or other payment apps correctly when initiating a payment transaction. The user should be able to complete the payment seamlessly.

Request for Assistance:

I would appreciate any insights, solutions, or suggestions on how to resolve this issue and successfully integrate Paytm payments into my Flutter app. Thank you for your help!