问错误:期望私钥为长度为32的Uint8Array

EN

var Tx= require('ethereumjs-tx').Transaction
const Web3=require('web3')
const web3= new Web3('HTTP://127.0.0.1:7545') 
const account1='0x06e61BDdC2a45A7523C62c0DcC4E15D842BBa9BA'
const account2='0x886ffD053C1eC72C10fA6FE1c916cb5A23313A76'
const privateKey_acc1=Buffer.from('b1292b419cb954157ba5a9f3385fc57a6ff31cdf80afe96d13af7335b5c55436')
// const privateKey_acc2=Buffer.from('d7adcf5175859f7244eeff812d456600bc938ff0ad8f7fa4fdfde946481f968f')
console.log(privateKey_acc1);
web3.eth.getBalance(account1,(err,res)=>{
    console.log(web3.utils.fromWei(res));
})
web3.eth.getTransactionCount(account1,(err,txCount)=>{
    // build the transction
    const obej={
        nonce:web3.utils.toHex(txCount),
        to:account1,
        value:web3.utils.toHex(web3.utils.toWei("1")),
        gassLimit:web3.utils.toHex(2100),
        gasPrice:web3.utils.toHex(2100)
    }
    // sign 
    const tx= new Tx(obej) 
    // tx.sign(privateKey_acc1)
    const serialtrans=tx.serialize()
    const raw='0x'+serialtrans.toString('hex')
    // console.log(raw);
    // broadcast transaction
    web3.eth.sendSignedTransaction(raw,(err,txhash)=>{
        // console.log('hash',txhash);
    })
}) 

if (!cond) throw new Error(msg)
             ^

Error: Expected private key to be an Uint8Array with length 32
    at assert (/Users/yaksheshgupta/node_modules/secp256k1/lib/index.js:18:20)
    at isUint8Array (/Users/yaksheshgupta/node_modules/secp256k1/lib/index.js:31:7)
    at Object.ecdsaSign (/Users/yaksheshgupta/node_modules/secp256k1/lib/index.js:254:7)
    at Object.exports.sign (/Users/yaksheshgupta/node_modules/ethereumjs-tx/node_modules/ethereumjs-util/dist/secp256k1v3-adapter.js:247:25)
    at Object.exports.ecsign (/Users/yaksheshgupta/node_modules/ethereumjs-tx/node_modules/ethereumjs-util/dist/signature.js:12:25)
    at Transaction.sign (/Users/yaksheshgupta/node_modules/ethereumjs-tx/dist/transaction.js:230:37)
    at Object.callback (/Users/yaksheshgupta/Desktop/JavaScript/web3_app.js:24:8)
    at sendTxCallback (/Users/yaksheshgupta/node_modules/web3-core-method/lib/index.js:541:29)
    at /Users/yaksheshgupta/node_modules/web3-core-requestmanager/lib/index.js:305:9
    at XMLHttpRequest.request.onreadystatechange (/Users/yaksheshgupta/node_modules/web3-providers-http/lib/index.js:98:13)
    at XMLHttpRequestEventTarget.dispatchEvent (/Users/yaksheshgupta/node_modules/xhr2-cookies/dist/xml-http-request-event-target.js:34:22)
    at XMLHttpRequest._setReadyState (/Users/yaksheshgupta/node_modules/xhr2-cookies/dist/xml-http-request.js:208:14)
    at XMLHttpRequest._onHttpResponseEnd (/Users/yaksheshgupta/node_modules/xhr2-cookies/dist/xml-http-request.js:318:14)
    at IncomingMessage.<anonymous> (/Users/yaksheshgupta/node_modules/xhr2-cookies/dist/xml-http-request.js:289:61)
    at IncomingMessage.emit (node:events:402:35)
    at endReadableNT (node:internal/streams/readable:1343:12)