# Getting cors error in sendRawTransaction function from reactjs localhost

**URL:** https://collective.flashbots.net/t/getting-cors-error-in-sendrawtransaction-function-from-reactjs-localhost/1347
**Category:** Relays
**Tags:** question
**Created:** [February 27, 2023, 11:47am UTC](https://collective.flashbots.net/t/getting-cors-error-in-sendrawtransaction-function-from-reactjs-localhost/1347 "2023-02-27T11:47:20Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![jatinder](https://collective.flashbots.net/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@jatinder](https://collective.flashbots.net/u/jatinder)
#### Post date: [February 27, 2023, 11:47am UTC](https://collective.flashbots.net/t/getting-cors-error-in-sendrawtransaction-function-from-reactjs-localhost/1347/1 "2023-02-27T11:47:20Z")

</div>

Hello everyone ,I need some help for transfer ethers using flashbots sendRawTransction on testnet from reactjs localhost.  
I am getting the cors error in sendRawTransaction request , can anyone help me out.  
Access to fetch at relay-goerli.flashbots from origin localhost:3000 has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: No ‘Access-Control-Allow-Origin’ header is present on the requested resource. If an opaque response serves your needs, set the request’s mode to ‘no-cors’ to fetch the resource with CORS disabled.

used relay-goerli.flashbots

sendTransaction = (  
toAddress,  
amount,  
chainId,  
message = “”,  
callback = null  
) =\> {  
return new Promise(async (resolve, reject) =\> {  
try {  
const authSigner = Wallet.createRandom();  
let result = null;  
// Flashbots provider requires passing in a standard provider  
const flashbotsProvider = await FlashbotsBundleProvider.create(  
this.PROVIDER, // a normal ethers.js provider, to perform gas estimiations and nonce lookups  
authSigner, // ethers.js signer wallet, only for signing request payloads, not transactions  
FLASHBOTS\_ENDPOINT  
// {  
// url: FLASHBOTS\_ENDPOINT,  
// headers:{  
// // “Accept”:“application/json, application/xml”,  
// “Content-Type”:“application/json”,  
// “Access-Control-Allow-Origin” : “_",  
// // “Access-Control-Allow-Credentials”: true,  
// // “Access-Control-Allow-Methods”: "_”,  
// },  
// // fetchOptions:{  
// // // mode : “no-cors”,  
// // // referrer : window.location.origin  
// // // “Cache-Control”: “no-cache”  
// // },  
// },  
);

```
    const block = await this.PROVIDER.getBlock();

    const blockBaseFee = Number(block.baseFeePerGas);
    const gasLimit = block.gasLimit;
    console.log("block gasLimit", gasLimit);
    const blockNumber = block.number;
    const maxBaseFeeInFutureBlock =
      FlashbotsBundleProvider.getMaxBaseFeeInFutureBlock(blockBaseFee, 6);
    const blocksTry = [];
    // this.PROVIDER.on("block", async (block) => {
    // console.log(`block: ${block}`);
    // const blockNumber = block;
    let targetBlock = Number(blockNumber);
    console.log("targetBlock", targetBlock);
    console.log("Starting to run the simulation...");
    const amountEther = Web3.utils.toWei(amount.toString(), "ether");
    console.log("amont ether", amountEther);
    const transactionBundle = [
      {
        signer: this.SIGNER,
        transaction: {
          chainId: chainId,
          type: 2,
          // maxFeePerGas: 300000000000,
          maxFeePerGas: PRIORITY_FEE.add(maxBaseFeeInFutureBlock),
          maxPriorityFeePerGas: PRIORITY_FEE,
          // gasLimit: gasLimit,
          gasLimit: 3000000,
          value: amountEther,
          data: ethers.utils.hexlify(ethers.utils.toUtf8Bytes(message)),
          to: toAddress,
        },
      },
    ];
    console.log("before sign data", transactionBundle);
    const signedTx = await flashbotsProvider.signBundle(
      transactionBundle
    );

    console.log("signedTx", signedTx);
    const sim = await flashbotsProvider.simulate(signedTx, targetBlock + 1);
    console.log("sim", sim);
    if ("error" in sim || sim.firstRevert !== undefined) {
      console.log("sim error", sim.error.message);
      reject("Transaction failed please try again!");
      // continue;
    }
    for (let i = 1; i <= 30; i++) {
      blocksTry.push(i);
      console.log("try block count", blocksTry.length);

      if (blocksTry.length >= 30) {
        reject("transaction failed please try again!");
        break;
      }

      // const block = await this.PROVIDER.getBlock(blockNumber)

      // console.log("block",block,"blockNumber",blockNumber);
   
    

      const bundleSubmission = await flashbotsProvider.sendRawBundle(
        signedTx,
        targetBlock + i
      );
      console.log("bundleSubmissionbundle", bundleSubmission);
      const bundleResolution = await bundleSubmission.wait();
      console.log("bundleResolutionbundleResolution", bundleResolution);
      if (bundleResolution === FlashbotsBundleResolution.BundleIncluded) {
        console.log(`Congrats, included in ${targetBlock}`);
        result = sim;
        console.log("success transaction", sim);
        resolve(sim);
        break;
        // console.log(JSON.stringify(sim, null, 2));
      } else if (
        bundleResolution ===
        FlashbotsBundleResolution.BlockPassedWithoutInclusion
      ) {
        console.log(`Not included in ${targetBlock}`);
      } else if (
        bundleResolution === FlashbotsBundleResolution.AccountNonceTooHigh
      ) {
        console.log("Nonce too high, bailing");
        reject("Transaction failed please try again!");
        break;
      }
    }

    // });
  } catch (error) {
    callback && callback(error?.message);
    reject(error?.message);
  }
});

```

};

please help me out.