I'm trying to call a contract method from the web3 interface in node.js (via testrpc) which should return a Boolean value.


This outputs an error:


throw errors.InvalidResponse(result);

Error: AssertionError: The field to must have byte length of 20

I also tried

contract_instance.my_method.call(function(error, result) {  

That outputs the same error. Whenever I comment out the result log the error disappears. In the testrpc logs the call is registered.

  • what is your function's code? – Badr Bellaj May 21 '17 at 23:24
  • function my_method() constant returns (bool) { return state; } which returns bool private state – Elias May 22 '17 at 15:58

Got the problem.

Instead of

var contract_instance = my_contract.at(["0xf6b0fc7bbb00fa5f47de4cd5d92157365276a0d3"]);

I had to use

var contract_instance = my_contract.at("0xf6b0fc7bbb00fa5f47de4cd5d92157365276a0d3");

| improve this answer | |

your code doesn't seem to be the source of your error, its seems to be a testrpc problem i advise you to open an issue on their github.

I've deployed a simple contract on Ropsten testnet

pragma solidity ^0.4.2;

        contract test{

            bool private state;
            function my_method() constant returns (bool) { return state; }


calling the my_method using Web3js(+Metamask) it works perfectly :

contract.my_method(function(error, result){

the whole code test is available here

| improve this answer | |

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