Note: This question is related to this : "Updated :" How to see "output" of "web3.personal.sign" in "browser"? ("Method personal_sign not supported")

I do following steps to sign a message using web3.personal.sign. However, I am not to MetaMask. (Note: apparently, web3.personal.sign is not supported by testRPC.) Here are steps that I do:

(1) I open cmd and run testrpc

(2) I click on MetaMask icon and selecting localhost 8545

(3) I select one of private keys generated by testrpc

(4) I select import account from MetaMask and paste this private key in text box of Paste your private key string here

(5) now balance of this address is 100 eth

(6) I insert this address (public key) in web3.personal.sign function to sign the message (Please see the full code below)

(7) I open html file by Google Chrome

(8) I receive this messages : No web3? You should consider trying MetaMask! and Error: Method personal_sign not supported. Here is screen shot: https://ibb.co/i93oRy

Here is the full code for signing a message using web3.personal.sign:

<!doctype html>

<html lang="en">
  <meta charset="utf-8">
  <title>EthereumJS - Browser Example</title>

  <script src="https://rawgit.com/ethereumjs/browser-builds/master/dist/ethereumjs-abi/ethereumjs-abi-0.6.5.js"></script> 
  <script src="https://rawgit.com/ethereum/web3.js/develop/dist/web3.js"></script> 
  <script src="https://cdn.jsdelivr.net/gh/ethereum/web3.js/dist/web3.min.js"></script>


window.addEventListener('load', function() {

   // Checking if Web3 has been injected by the browser (Mist/MetaMask)
  if (typeof web3 !== 'undefined') {
    // Use Mist/MetaMask's provider
    web3 = new Web3(web3.currentProvider);
  } else {
    console.log('No web3? You should consider trying MetaMask!')
    // fallback - use your fallback strategy (local node / hosted node + in-dapp id mgmt / fail)
    web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

//  var Web3 
//  web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

  function constructPaymentMessage(contractAddress, amount) 
  return ethereumjs.ABI.soliditySHA3(
    ["address", "uint256"],
    [contractAddress, amount],

  var message = constructPaymentMessage("message to be signed", 100);

  web3.personal.sign("0x" + message.toString("hex"), "0x01e7D1D50804fDc2fD5A134081076A8E487Ca747", function(err, signature) {
  // Be sure to make use of the signature only here.
  // It will not be defined until this callback is invoked.


Apparently, I am not connected to MetaMask and if so, How can I solve this problem?

Here is screen shot of MetaMask when is opened and connected to localhost 8545 (As you can see the balance of testRPC address is 100 eth) :

enter image description here

  • 1
    Show us a screenshot of your Metamask extension opened and connected to the network Jul 22, 2018 at 23:06
  • 1
    When you go to this page using chrome, what does your console say? Jul 22, 2018 at 23:15
  • @Shawn Tabrizi Web3 Detected! MetamaskInpageProvider screen shot : ibb.co/gZfwDd
    – Questioner
    Jul 22, 2018 at 23:18

1 Answer 1


A web server is required for a Metamask to interact with your webpage:

Http(s) - Web Server Required

Due to browser security restrictions, we can't communicate with dapps running on file://. Please use a local server for development.

Deploy your page to a local server in order to detect Metamask.

  • Yes apparently. This answer ethereum.stackexchange.com/a/46400/23024 also says this. However it suggests also using https://mainnet.infura.io/<APIKEY> instead of localhost 8545 if I run my page locally. So, can i use "https://mainnet.infura.io/noapikey" that is used in the page you shared ? Thanks
    – Questioner
    Jul 22, 2018 at 23:28
  • also if i connect to Ropsten by Parity but i use localhost 8545 in my html file, Does it work ? Thanks
    – Questioner
    Jul 22, 2018 at 23:34
  • 1
    The problem is if you use infura as your connection to the network, you will not have an "account" loaded with your web3 provider. You can of course put your private key and stuff within your code so that you are able to use your account, but usually using something like Metamask is better. Infura is a good replacement if you are simply doing read operations. Jul 22, 2018 at 23:37
  • Thank you, so in this case, I have to use ex. Parity to connect to ex. Ropsten and then use web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545")); in top of JavaScript code and running this JS file using node filename.js ? Is there any better way? Thanks
    – Questioner
    Jul 23, 2018 at 9:08

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