I don't know why but i'm not able to perform transaction with this code. please help me out i'm stuck. i just have to call setter method of my contract with some arguments.

router.post("/set", async function (request, response) {

let fromAddress = request.body.from_address;
let privateKey = request.body.from_private_key;
let contractAddress = request.body.contract_address;
let caseId = request.body.case_id;
let userIdentityAddress = request.body.user_identity_address;
let complaintType = request.body.complaint_type;
let complaintNature = request.body.complaint_nature;
let complaintDescription = request.body.complaint_description;
let document = request.body.document;

// const sleep = (milliseconds) => {
//     return new Promise(resolve => setTimeout(resolve, milliseconds))
// }

const contract = await new web3.eth.Contract((abi), contractAddress);
let count = web3.eth.getTransactionCount(fromAddress);
web3.eth.defaultAccount = fromAddress;

const tx_builder = contract.methods.createCase(

let encoded_tx = tx_builder.encodeABI();

let gasPrice = await web3.eth.getGasPrice();
let gasLimit = 500000;
let transactionObject = {
    "nonce": web3.utils.toHex(count),
    "from": fromAddress,
    "gasPrice": web3.utils.toHex(gasPrice),
    "gasLimit": web3.utils.toHex(gasLimit),
    "to": contractAddress,
    "data": encoded_tx,
    "chainId": 0x03

web3.eth.accounts.signTransaction(transactionObject, privateKey, function (error, signedTx) {
    if (error) {
        console.log('thiss', error);
        // handle error
    } else {
            .on('receipt', function (receipt) {
                console.log('heloo', receipt)

Error Response: { messageHash: '0x7c02b35df7d5c6eea7dba25fe38fe29b224e4e38eff2dda76ca70629ac330f44', v: '0x2a', r: '0x5675ff3d56b6b57c18dcc35fc3396a12bb1c3bb338537047ff10bea687ae9e21', s: '0xb38d8a3b19ba34aea031b9e286fa0e4733dfb6640313d594321d626f5c87110',

If you see here 's' is missing one hex character

(node:26007) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Returned error: invalid argument 0: json: cannot unmarshal hex string of odd length into Go value of type hexutil.Bytes (node:26007) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

After logging transactionObject and signedTx

enter image description here

1 Answer 1


My guess is that the (or at least an?) issue is here:

let count = web3.eth.getTransactionCount(fromAddress);

You're missing an await, so you're not getting a proper nonce. Perhaps that's causing an encoding problem of some sort later when signing the transaction object.

If that doesn't resolve the issue, I recommend logging transactionObject and then signedTx to see what's in those variables.

  • 1
    There's also a missing await on call to contract.methods.createCase. An attempt to use the returned value from this call is made before an attempt to use the returned value which you have mentioned - count. Jun 14, 2019 at 21:29
  • 1
    Addressed in a comment on your (now deleted) answer, but contract.methods.createCase does not return a Promise.
    – user19510
    Jun 14, 2019 at 21:33
  • Thanks for your answer but its not a issue of await i think. i have checked it again with await but still the same error. Jun 14, 2019 at 21:59
  • I have added Image of transactionObject after logging. Please see question again. Thanks Jun 14, 2019 at 22:06
  • I'm not 100% sure what you're logging, but it looks like maybe signedTx is a Promise? If so, make sure to await it first.
    – user19510
    Jun 14, 2019 at 22:12

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