I am making a flash loan request using web3 , truffle and keep getting the error in an event listener:

The current provider doesn't support subscriptions: HDWalletProvider.

I am connecting to the ropsten test network.

I am using the code below to connect to get emitted events in a smart contract:

const web3 = new Web3();
const eventProvider = new Web3.providers.WebsocketProvider(wss);
eventProvider.on('error', e => {
    console.error('WS Infura Error', e);

eventProvider.on('connect', function () {
        console.log('WSS Connected');

eventProvider.on('end', e => {
    console.log('WS closed');
    console.log('Attempting to reconnect...');

       eventProvider = new Web3.providers.WebsocketProvider(wss);

eventProvider.on('connect', function () {
        console.log('WSS Reconnected');

The request is:

 contract1.methods.flashloan( args_of_my_use_case ).send({
              from: addr, //designated Metamask wallet address
              gas: gasCost,
              value: 0,
              nonce: accountNonce,
            function (error, data) {
                 invariant.currentlyTrading = false;
                 obj.nowTrading = false;
               console.log('arb data => ', data, '   arb error => ' ,error, appendText);

The connection works and events get fired but one of the responses from a flash loan request is:

Error: The current provider doesn't support subscriptions: HDWalletProvider

My truffle config is:

const dotenv = require('dotenv');
const fs = require('fs');
const envConfig = dotenv.config({silent: true});

 const HDWalletProvider = require('@truffle/hdwallet-provider');
 const infuraKey = process.env.INFURA_API_KEY;

const ethPubAddr = process.env.ETH_PUBLIC_ADDRESS;
 const mnemonic = process.env.METAMASK_PVT_KEY; 

 console.log("mnemonic -->" , mnemonic);

module.exports = {
  networks: {
    // Useful for testing. The `development` name is special - truffle uses it by default
    // if it's defined here and no other network is specified at the command line.
    // You should run a client (like ganache-cli, geth or parity) in a separate terminal
    // tab if you use this network and you must also set the `host`, `port` and `network_id`
    // options below to some value.
    mainnet: {
      provider: function() {
        return new HDWalletProvider(mnemonic, "https://mainnet.infura.io/v3/"+infuraKey);
      network_id: 1,
      from: ethPubAddr

    ropsten: {
      provider: function() {
         return new HDWalletProvider(mnemonic, "wss://ropsten.infura.io/ws/v3/"+infuraKey);
      network_id: 3,
      from: ethPubAddr,   
      gas: 6800000, // Current Ropsten gas limit. See https://ropsten.etherscan.io/block/3141628
      gasPrice: 20000000000 // 1.1 GWei - based on the lower end of current txs getting into blocks currently on Ropsten.
   //   gasLimit: 8000000

    development: {
      host: "",     // Localhost (default: none)
      port: 8545,            // Standard Ethereum port (default: none)
      network_id: "*",       // Any network (default: none)


  // Set default mocha options here, use special reporters etc.
  mocha: {
    // timeout: 100000

  // Configure your compilers
  compilers: {
    solc: {
       version: '0.6.10',    // Fetch exact version from solc-bin (default: truffle's version)
      // docker: true,        // Use "0.5.1" you've installed locally with docker (default: false)
     settings: {          // See the solidity docs for advice about optimization and evmVersion
       /* optimizer: {
          enabled: true,
          runs: 2
      //  evmVersion: "byzantium"


1 Answer 1


Subscriptions are only supported by WebSockets provider. The URL you are giving is for HTTP provider

        return new HDWalletProvider(mnemonic, "https://mainnet.infura.io/v3/"+infuraKey);`

Change https:// to wss://.

  • 2
    Hi @Mikko, thanks for answering. I apologize for not mentioning that I am on ropsten a test network. It is actually set to wss in my code. I still have the issue though; even with the wss. I will edit the question to show that now. Commented Jun 25, 2020 at 15:53
  • Ok gotcha. Does your code work if you leave out HDWalletProvider and just use WSS provider directly? It almost sounds like Web3.js has a bug to detect this. Commented Jun 26, 2020 at 8:22
  • I just searched web3.js repo quickly how this is detected: github.com/ethereum/web3.js/blob/… - might be that a patch for HDWalletProvider might be needed if it lacks on function Commented Jun 26, 2020 at 8:25
  • 1
    Yes. I do not remember how it should look like, but web3.js docs should have an example. I have a gut feeling HDWalletProvider is the culprint. Commented Jun 26, 2020 at 9:12
  • 1
    If this is the case then I suggest you file an issue directly in Truffle github repository. Commented Jun 27, 2020 at 8:13

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