I am able to use the web3.py library and i am able to deploy the contract directly using my node in ethereum.

I created my solidity code in remix and copied the abi in the etherum console to deploy the code. I got the address of the contract as well.

My solidity code is as follows.

pragma solidity ^0.4.0;

//For testing use the below data

contract bidding {

struct bid {
    string bidderName;
    uint grainId;
    uint bidAmount;
    uint bidTime;

mapping (uint => bid) bidInfos;
uint[] public bidIds;

function addBid(
    uint _bidId,
    string _bidderName, 
    uint _grainId, 
    uint _bidAmount
) public {
    var bid_info = bidInfos[_bidId];
    bid_info.bidderName = _bidderName;
    bid_info.grainId = _grainId;
    bid_info.bidTime= now;

    bidIds.push(_bidId) -1;

function getallBids() view public returns(uint[]) {
    return bidIds;

function getBid(uint _bidId) view public returns (string, uint, uint, uint) {
    return (

function getbidcount() view public returns (uint) {
    return bidIds.length;

I deployed in my etherum network and got the address as In my python i am using the web3 library.

from web3 import Web3, HTTPProvider, IPCProvider, WebsocketProvider
import json
web3 = Web3(IPCProvider())



This is the error i am getting.

  Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "D:\WinPython\python-3.5.4.amd64\lib\site-packages\web3\contract.py", line 1064, in transact
  File "D:\WinPython\python-3.5.4.amd64\lib\site-packages\web3\contract.py", line 1341, in transact_with_contract_function
txn_hash = web3.eth.sendTransaction(transact_transaction)
  File "D:\WinPython\python-3.5.4.amd64\lib\site-packages\web3\eth.py", line 244, in sendTransaction
  File "D:\WinPython\python-3.5.4.amd64\lib\site-packages\web3\manager.py", line 106, in request_blocking
raise ValueError(response["error"])
 ValueError: {'code': -32000, 'message': 'unknown account'}

I am doing a web3.personal.unlockAccount as well. still it is giving same error. There is only one account associated with my account as well. What am i doing wrong?

how to do the transaction so i can add a new bid from web3 in python and get the transaction hash.


1 Answer 1


Two things: Be sure that the checksum of the addresses is correct. you can do:

web3.toChecksumAddress('0xbcd8ffbb0f8a5410194ab5a3badf46caaa693098') // for the contract address

Also, try defining the from in transact, like this:

contract_bid.functions.addBid(10,"xyzz",1234,5600).transact({'from': 'your_account'})

Hope this helps.

  • Note that using toChecksumAddress wipes out any value of using the checksum. If you are copy/pasting an address from somewhere, see if you can find a checksummed version from that source. If you are using a source that does not provide a checksummed address, I recommend reporting it as a bug.
    – carver
    Jun 5, 2018 at 1:04
  • could you elaborate on this "wipes out any value of using the checksum"
    – Jaime
    Jun 5, 2018 at 8:52
  • If you run toChecksumAddress on an address with a busted checksum (which implies that the address is mis-entered), the method will simply "fix" the broken checksum. For example, try: ` Web3.toChecksumAddress('0xBCD8fFBb0F8a5410194AB5a3baDF46caaA693098')`.
    – carver
    Jun 5, 2018 at 16:28

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