using infura in truffle and get Error: Invalid JSON RPC response: ""

it is my first time to ask questions there ,please forgive my rudeness.

I using metamask, infura, and truffle to try to deploy the contract (the pet-shop-tutorial) to the ropsten testnet, all gone well but this.

that is the error information:

duchendeMacBook-Air:pet-shop-tutorial duchen$ truffle migrate --network ropsten --reset
Using network 'ropsten'.

Running migration: 1_initial_migration.js
  Replacing Migrations...
  ... 0x8bf66529dd4eb0c36a89ecec783808effad37ec4bc6dda9f9fe1a7f7cc219f3d
  Migrations: 0xb2ea93671103da9da0cc8018e4a262280e4944f0
Saving successful migration to network...
  ... 0xef35a32e4e13e9615c597527c082bb0f5cc32018bfa7a8ad4a03b9f8af9c59ce
Saving artifacts...
Running migration: 2_deploy_contracts.js
  Replacing Adoption...
  ... 0x4340c9d747dd134da705a6cc192432b0b4b75d0138a01ef21f5c955958a2bb05
  Adoption: 0x83544aff3420b9a1639fb9944449575f6135d915
Saving successful migration to network...
  ... 0x4774ad3d756e26aeaf047b5e19ae449ace957e3baf3578478c70c0aa951fa8e1
Saving artifacts...
/usr/local/lib/node_modules/truffle/build/cli.bundled.js:128857
var Module;if(!Module)Module=(typeof Module!=="undefined"?Module:null)||{};var moduleOverrides={};for(var key in Module){if(Module.hasOwnProperty(key)){moduleOverrides[key]=Module[key]}}var ENVIRONMENT_IS_WEB=false;var ENVIRONMENT_IS_WORKER=false;var ENVIRONMENT_IS_NODE=false;var ENVIRONMENT_IS_SHELL=false;if(Module["ENVIRONMENT"]){if(Module["ENVIRONMENT"]==="WEB"){ENVIRONMENT_IS_WEB=true}else if(Module["ENVIRONMENT"]==="WORKER"){ENVIRONMENT_IS_WORKER=true}else if(Module["ENVIRONMENT"]==="NODE"){ENVIRONMENT_IS_NODE=true}else if(Module["ENVIRONMENT"]==="SHELL"){ENVIRONMENT_IS_SHELL=true}else{throw new Error("The provided Module['ENVIRONMENT'] value is not valid. It must be one of: WEB|WORKER|NODE|SHELL.")}}else{ENVIRONMENT_IS_WEB=typeof window==="object";ENVIRONMENT_IS_WORKER=typeof importScripts==="function";ENVIRONMENT_IS_NODE=typeof process==="object"&&"function"==="function"&&!ENVIRONMENT_IS_WEB&&!ENVIRONMENT_IS_WORKER;ENVIRONMENT_IS_SHELL=!

Error: Invalid JSON RPC response: ""
 at Object.InvalidResponse (/Users/duchen/node_modules/truffle-hdwallet-provider/node_modules/web3/lib/web3/errors.js:35:16)
    at XMLHttpRequest.request.onreadystatechange (/Users/duchen/node_modules/truffle-hdwallet-provider/node_modules/web3/lib/web3/httpprovider.js:115:32)
    at XMLHttpRequestEventTarget.dispatchEvent (/Users/duchen/node_modules/xhr2/lib/xhr2.js:64:18)
    at XMLHttpRequest._setReadyState (/Users/duchen/node_modules/xhr2/lib/xhr2.js:354:12)
    at XMLHttpRequest._onHttpRequestError (/Users/duchen/node_modules/xhr2/lib/xhr2.js:544:12)
    at ClientRequest.<anonymous> (/Users/duchen/node_modules/xhr2/lib/xhr2.js:414:24)
    at emitOne (events.js:116:13)
    at ClientRequest.emit (events.js:211:7)
    at TLSSocket.socketErrorListener (_http_client.js:387:9)
    at emitOne (events.js:116:13)

and this is my code in truffle.js:

var HDWalletProvider = require("truffle-hdwallet-provider");
var mnemonic = "candy maple cake sugar pudding cream honey rich smooth crumble sweet treat";
module.exports = {
  // See <http://truffleframework.com/docs/advanced/configuration>
  // for more about customizing your Truffle configuration!
  networks: {
    development: {
      host: "127.0.0.1",
      port: 7545,
      network_id: "*" // Match any network id
    },
      ropsten: {
      provider:function(){
      return new HDWalletProvider(mnemonic, "https://ropsten.infura.io/epDGgTgqhFlsPTwmmVC0")
      },
      network_id: 3,
      gas:499000,
      gasPrice:1000000000000
    }
  }
};

I followed the steps from http://truffleframework.com/tutorials/using-infura-custom-provider but it seemed it has some problems, thank you for your answers.

[roderik]

Already a small observation:

I added a console log in HDWalletProvider to log the rpc url used in the constructor.

using provider: new HDWalletProvider(), it cleanly logs the URL once using provider: () => return new HDWalletProvider(), it logs the url multiple times per migration (2x per artifact.require)

Seems like the () => form is not such a good idea

[Leon-Africa]

rm node_modules/

rm package.json

rm package-lock.json

Create an empty package.json file like this:

{
  "dependencies": { 
  }
}

Update node and npm Ensure latest stable version node installed - currently 12.13.1

The update npm:

npm install -g npm

(restart terminal)

truffle-hdwallet-provider is deprecated: https://www.npmjs.com/package/truffle-hdwallet-provider

Instead use @truffle/hdwallet-provider: https://www.npmjs.com/package/@truffle/hdwallet-provider

(while in your project dir containing the package.json):

npm install @truffle/hdwallet-provider --save

In your truffle-config.js:

var HDWalletProvider = require("@truffle/hdwallet-provider");

Then:

truffle migrate --network rinkeby