[Ethereum] web3 eth.sign error: invalid address

metamaskweb3js

I am getting an error when trying to sign data with web3 and metamask

signed_data = myWeb3.eth.sign("hello", web3.eth.accounts[0])

web3.eth.accounts[0] is populated with my account number in string form

Results in error:

Uncaught Error: invalid address
at c (inpage.js:1)
at inpage.js:1
at Array.map (<anonymous>)
at o.formatInput (inpage.js:1)
at o.toPayload (inpage.js:1)
at n.e [as sign] (inpage.js:1)
at test.html:12

Best Answer

Take a look here at a complete working sample of signing and recovering messages with Web3.js and MetaMask:

https://github.com/shawntabrizi/web3js-sign-and-verify-ethereum

You can play around with a deployed version of this code here:

https://shawntabrizi.com/ethsign/

There could be a few problems here with your code, which is hard to decipher with the information you provided:

  • Using web3.eth.sign vs web3.eth.personal.sign. Starting with Web3.js 1.0, using personal where possible is much better, and this is what should be used for MetaMask accounts

  • web3.eth.accounts[0] not being populated. In Web3.js 1.0, this value is not populated by default. Instead you need to get accounts using something like:

    var accounts = await web3.eth.getAccounts()
console.log(accounts[0])

  • Order of your parameters. Depending on the version of Web3.js you are using, the order of the parameters change:

    web3.eth.sign(address, dataToSign [, callback]) // web3.js 0.x.x

web3.eth.sign(dataToSign, address [, callback]) // web3.js 1.0

Given the number of issues, it would be best you start with a working sample like the one I linked above.

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