I am playing around with Metamask and the web3.js API using the Google Chrome console. However, I have two issues:

1) I am trying to send a simple transaction using Ganache GUI (localhost 7545) and I am entering the code below:

> ethereum.enable()

> web3.currentProvider.selectedAddress

> var transaction = {
    from: web3.currentProvider.selectedAddress,
    to: "0xA8b62F503181D9A56683129de1B98ea4Bf143a40",
    value: web3.toWei("1", "ether")
> web3.eth.sendTransaction(transaction)

Then I am getting the error message below:

> Uncaught Error: The MetaMask Web3 object does not support synchronous methods like eth_sendTransaction without a callback parameter. See https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md#dizzy-all-async---think-of-metamask-as-a-light-client for details.
    at MetamaskInpageProvider._sendSync (inpage.js:1)
    at MetamaskInpageProvider.send (inpage.js:1)
    at Proxy.t.send (inpage.js:1)
    at a.send (inpage.js:1)
    at w.e [as sendTransaction] (inpage.js:1)
    at <anonymous>:1:10

2) Also note that the web3.version seems to be 0.20.7 whereas when I check this website https://web3js.readthedocs.io/en/v1.2.4/, the new version of the web3.js API seem to be 1.2.4. Is there a way to update the web3.js API version in the chrome console while using the Metamask extension? Note that I have tried to enter this in the console web3 = new Web3(web3.currentProvider) but the web3.version remains 0.20.7.

In terms of priority 1) is more critical I believe.

Could you please assist.

Thank you

  • You should make another question for your second question. Jan 3, 2020 at 13:27

1 Answer 1


The answer to your first question seems to be quite straight forward: you need to provide a callback to the function. It is what the error tells you to do, moreover, the documentation says a callback can be added.


web3.eth.sendTransaction(transaction, () => {
// your callback
  • Thank you very much for clarifying the situation. I have followed your recommendations and it worked nicely. FYI to close the thread, I have used the code below web3.eth.sendTransaction(transaction, function(error, hash){ if (error) console.error(error); else { console.log(hash); res.json(hash); } });
    – user32379
    Jan 5, 2020 at 1:28
  • @Weisel2095 if the answer is correct, please mark it as the correct answer. Jan 6, 2020 at 8:26

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