throw errors.InvalidResponse(result);
        ^

Error: The method eth_sendTransaction does not exist/is not available

const contractFunction = contract.greet({from:web3.eth.defaultAccount},"hello all devs");

const functionAbi = contractFunction.encodeABI();

let estimatedGas;
let nonce;

console.log("Getting gas estimate");

contractFunction.estimateGas({from: account}).then((gasAmount) => {
 estimatedGas = gasAmount.toString(16);

 console.log("Estimated gas: " + estimatedGas);

 web3.eth.getTransactionCount(account).then(_nonce => {
   nonce = _nonce.toString(16);

   console.log("Nonce: " + nonce);
   const txParams = {
     gasPrice: '0x09184e72a000',
     gasLimit: 3000000,
     to: contract_Address,
     data: functionAbi,
     from: account,
     nonce: '0x' + nonce
   };
   const tx = new Tx(txParams);
   signed_tx = web3.eth.account.signTransaction(tx, privateKey)
   tx_hash= web3.eth.sendRawTransaction(signed_tx.rawTransaction)
   tx_receipt = web3.eth.waitForTransactionReceipt(tx_hash)
   //tx.sign(privateKey);
   console.log(tx_receipt)