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

web3js

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?

Best Answer

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 web3@0.20.1 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.

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