RangeError: private key length is invalid: secp256k1.sign(msgHash, privateKey); - ethereum

Question

Getting below error while signing the transaction on ethereum network:
E:\Web3\node_modules\ethereumjs-util\dist\index.js:369
var sig = secp256k1.sign(msgHash, privateKey);
^
RangeError: private key length is invalid
at Object.exports.ecsign (E:\Web3\node_modules\ethereumjs-util\dist\index.js:369:23)
at Transaction.sign (E:\Web3\node_modules\ethereumjs-tx\es5\index.js:252:23)
at Object.web3.eth.getTransactionCount [as callback] (E:\Web3\app3.js:264:8)
at sendTxCallback (E:\Web3\node_modules\web3-core-method\src\index.js:484:29)
at E:\Web3\node_modules\web3-core-requestmanager\src\index.js:147:9
And here is the web3 code responsible for this error. I am converting the private key values to 'hex' representation but it still not working out.
const Tx = require('ethereumjs-tx')
const Web3 = require('web3')
const web3 = new Web3('https://ropsten.infura.io/tBIZU6erdu0roIzShVDM')
const account1='0xceAbcE5eE63212e7d4fAf9eB522d2B7b5886bF1F'
const account2='0x5F16088a3dec5c07E02317B403472c9ff5335912'
console.log(process.env.PRIVATE_KEY_1)
const privateKey1 = Buffer.from(process.env.PRIVATE_KEY_1, 'hex')
const privateKey2 = Buffer.from(process.env.PRIVATE_KEY_2, 'hex')
console.log(privateKey1)
console.log(privateKey2)
contractABI = [
{
"constant": true,
"inputs": [],
"name": "name",
"outputs": [
{
"name": "",
"type": "string"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_spender",
"type": "address"
},
{
"name": "_value",
"type": "uint256"
}
],
"name": "approve",
"outputs": [
{
"name": "success",
"type": "bool"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "totalSupply",
"outputs": [
{
"name": "",
"type": "uint256"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_from",
"type": "address"
},
{
"name": "_to",
"type": "address"
},
{
"name": "_value",
"type": "uint256"
}
],
"name": "transferFrom",
"outputs": [
{
"name": "success",
"type": "bool"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "standard",
"outputs": [
{
"name": "",
"type": "string"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": true,
"inputs": [
{
"name": "",
"type": "address"
}
],
"name": "balanceOf",
"outputs": [
{
"name": "",
"type": "uint256"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "symbol",
"outputs": [
{
"name": "",
"type": "string"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_to",
"type": "address"
},
{
"name": "_value",
"type": "uint256"
}
],
"name": "transfer",
"outputs": [
{
"name": "success",
"type": "bool"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [
{
"name": "",
"type": "address"
},
{
"name": "",
"type": "address"
}
],
"name": "allowance",
"outputs": [
{
"name": "",
"type": "uint256"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"inputs": [
{
"name": "_initialSupply",
"type": "uint256"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "constructor"
},
{
"anonymous": false,
"inputs": [
{
"indexed": true,
"name": "_from",
"type": "address"
},
{
"indexed": true,
"name": "_to",
"type": "address"
},
{
"indexed": false,
"name": "_value",
"type": "uint256"
}
],
"name": "Transfer",
"type": "event"
},
{
"anonymous": false,
"inputs": [
{
"indexed": true,
"name": "_owner",
"type": "address"
},
{
"indexed": true,
"name": "_spender",
"type": "address"
},
{
"indexed": false,
"name": "_value",
"type": "uint256"
}
],
"name": "Approval",
"type": "event"
}
]
const contractAddress = '0x30a8999Cb4c766fD6BA21723679466169710f053'
const contract = new web3.eth.Contract(contractABI, contractAddress)
const data = contract.methods.transfer(account2, 1000).encodeABI()
web3.eth.getTransactionCount(account1, (err, txCount) => {
//Build Tx
const txObject = {
nonce: web3.utils.toHex(txCount),
gasLimit: web3.utils.toHex(800000),
gasPrice: web3.utils.toHex(web3.utils.toWei('10', 'gwei')),
to: contractAddress,
data: data
}
//sign the Tx
const tx = new Tx(txObject)
tx.sign(privateKey1)
const serializedTransaction = tx.serialize()
const raw = '0x' + serializedTransaction.toString('hex')
//Broadcast Tx
web3.eth.sendSignedTransaction(raw, (err, txHash) => {
console.log('err: ',err,'txHash:', txHash)
})
})
I even tried without using the 'hex' conversion of private keys, also I tried removing '0x' from the private key values but nothing is working out.
Can anyone suggest, what can be issue here as I am new to Web3 and trying my level best to understand it.

Answer 1

I know it way to late but for anyone searching this, try :const privateKey = Buffer.from(process.env.PRIVATE_KEY, "hex");
It worked for me ;)

Answer 2

Try sending the private key removing the '0x'
Maybe like this:
process.env.PRIVATE_KEY_1.substr(2);
Hope it helps!