Invalid JSON RPC response: undefined, when running web3.eth.accounts (Node)

Question

I'm very new Ethereum and trying to follow this tutorial:

https://medium.com/@mvmurthy/full-stack-hello-world-voting-ethereum-dapp-tutorial-part-1-40d2d0d807c2

But when I run:

web3.eth.accounts

I get an error:

Error: Invalid JSON RPC response: undefined
    at Object.InvalidResponse (/Users/me/Ethereum/hello_world_voting/node_modules/web3/lib/web3/errors.js:38:16)
    at HttpProvider.send (/Users/me/Ethereum/hello_world_voting/node_modules/web3/lib/web3/httpprovider.js:95:18)
    at RequestManager.send (/Users/me/Ethereum/hello_world_voting/node_modules/web3/lib/web3/requestmanager.js:58:32)
    at Eth.get [as accounts] (/Users/me/Ethereum/hello_world_voting/node_modules/web3/lib/web3/property.js:107:62)
    at repl:1:9
    at ContextifyScript.Script.runInThisContext (vm.js:44:33)
    at REPLServer.defaultEval (repl.js:239:29)
    at bound (domain.js:301:14)
    at REPLServer.runBound [as eval] (domain.js:314:12)
    at REPLServer.onLine (repl.js:433:10)

Everything up until this worked.

Looks like an associated question here, but I don't have enough background to understand and follow it.

Error: Invalid JSON RPC response: undefined from node web3.js app

Can anyone point me in the right direction?

Answer 1

I had the same issue, and just found the solution. This response happens when testrpc is not running, as stated by @Abhishek in the comments.

To solve it, the trick is to run testrpc in another terminal window:

Install web3 and testrpc packages: npm install ethereumjs-testrpc [email protected] In the same terminal window, run testrpc: node_modules/.bin/testrpc Open a NEW terminal window (with the first one still open and running), and run node :

mahesh@projectblockchain:~/hello_world_voting$ node
> Web3 = require('web3')
> web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

Finally, you can run: > web3.eth.accounts

You will get the list of accounts.

Answer 2

I had the same issue, but i solved this problem as: before run web3.eth.accounts, you need to open new terminal, go to your folder project and run command testrpc, after that you can run web3.eth.accounts without error

Answer 3

I had this problem but for a different reason. I was trying to access Ganache (which is now also TestRPC) using an HTTPS URL instead of an HTTP URL:

Wrong:

https://127.0.0.1:8545

Right:

http://127.0.0.1:8545

Assuming you have Ganache listening on port 8545.

TIP: Grab the URL right from the Ganache GUI. You'll see it at the top of the screen. If you are using the Ganache CLI version, grab it from the startup messages you should see in the command window you launched it from. Then just paste it into your web3 object initialization line when you create that object in your Javascript code:

let web3 = new Web3(new Web3.providers.HttpProvider("http://127.0.0.1:8545"));

Answer 4

To make access to web3 and use it to retrieve a list of accounts that can be automatically created for you as part of the local ganache network.

You start out by defining a beforeEach() statement where you can add an arrow syntax and add some comments that can guide you in completing these tasks.

So how do you gain access to web3 to gain access to all unlocked accounts?

Inside your beforeEach() you access your web3 module which can be used with many different types of cryptocurrencies. In this case you are looking for ethereum currency so it will look like this: web3.eth.

Then you will want to access the getAccounts() function. web3 is asynchronous in nature, which means it will always be returning a promise and you want it to return a promise with a list of accounts that you care about. So you have to implement async/await like so below:

const assert = require('assert');
const ganache = require('ganache-cli');
const Web3 = require('web3');

const provider = ganache.provider();
const web3 = new Web3(provider);

let accounts;

beforeEach(async () => {
  // Get a list of accounts
  accounts = await web3.eth.getAccounts();

Answer 5

I had the same issue. Ganache was running on http://127.0.0.1:7545

I replaced this line

const web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:7545"))

with this one:

const web3 = new Web3(new Web3.providers.HttpProvider("http://127.0.0.1:7545"))

And it worked

Answer 6

Go to settings in Ganache Desktop app and change hostname in server settings. Settings -> server -> hostname

set [All Interfaces] then try, running your js file with node following.

const Web3 = require("web3");

var web3 = new Web3(new Web3.providers.HttpProvider("http://0.0.0.0:7545"));
try {
  console.log(web3.eth.accounts);
} catch (e) {
  console.log(e.message);
}