Sushiswap pairadress contract .estimateGas.swap throws server error

Question

I'm working on an arbitrage trading bot, using ethers.js in my JavaScript file that is calling my flashloan smartcontract, testing on Kovan.

I deployed a flashloan smartcontract on the kovan network. 0x236f6860b31F6226d5937EC0Bd9465B12C2b20cA

In my JavaScript file, I want to estimate the gas that will be used when I call this contract. However, I'm always receiving a server error.

When I call this flashloan contract from my pair contract address, it does work. So I assume the problem is not inside the flashloan smartcontract that is called.

This is part of my code:

const provider = new ethers.providers.InfuraProvider("kovan", kovanKey);
const wallet = new ethers.Wallet(privateKey, provider);
let pairAd2 = "0x052AE8b0F7E5c610937920e46ED265c2063Cb7B8";
let  uniToken0Token1 = new ethers.Contract(
          pairAd2,
           UniV2Pair.abi, wallet,
         );
const gl = await uniToken0Token1.estimateGas.swap(
               0,
               10,
               flashLoanerAddress,
               ethers.utils.toUtf8Bytes('1')
             );

This will throw this error:

processing response error (body="{\"jsonrpc\":\"2.0\",\"id\":45,\"error\":{\"code\":-32016,\"data\":\"Reverted\",\"message\":\"The execution failed due to an exception.\"}}", error={"code":-32016,"data":"Reverted"}, requestBody="{\"method\":\"eth_estimateGas\",\"params\":[{\"from\":\"0x8da6ae9837c8bb55fc6c0a0ec1ee3000942af8f4\",\"to\":\"0x4d027027af6dfa0a14332223fedfc8289d205088\",\"data\":\"0x022c0d9f0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000a000000000000000000000000236f6860b31f6226d5937ec0bd9465b12c2b20ca000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000013100000000000000000000000000000000000000000000000000000000000000\"}],\"id\":45,\"jsonrpc\":\"2.0\"}", requestMethod="POST", url="https://kovan.infura.io/v3/.................", code=SERVER_ERROR, version=web/5.5.1)
 reason: 'processing response error',
  code: 'SERVER_ERROR',
  body: '{"jsonrpc":"2.0","id":45,"error":{"code":-32016,"data":"Reverted","message":"The execution failed due to an exception."}}',
.
.
.
 code: -32016,
    data: 'Reverted'
  },
  requestBody: '{"method":"eth_estimateGas","params":[{"from":"0x8da6ae9837c8bb55fc6c0a0ec1ee3000942af8f4","to":"0x4d027027af6dfa0a14332223fedfc8289d205088","data":"0x022c0d9f0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000a000000000000000000000000236f6860b31f6226d5937ec0bd9465b12c2b20ca000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000013100000000000000000000000000000000000000000000000000000000000000"}],"id":45,"jsonrpc":"2.0"}',
  requestMethod: 'POST',
  url: 'https://kovan.infura.io/v3/......................'

Which I don't understand, I've been searching for days.

Or how can I see more information maybe about the error/cause?

Answer 1

here are some steps you can take, but not an accurate answer. maybe try getting your gas price from an oracle like https://www.gasprice.io/ then maybe add the right slippage percentage. if you haven't ,have a a look at how sushiswap subgraph works. https://thegraph.com/hosted-service/subgraph/sushiswap/exchange

if you look through sushiswap's interface on github, you can sort through various methods for 'gas', like run a search/find for the method calculateGasMargin and see how sushiswap is doing it. you can see they're using 'gasEstimate' instead of 'gasPrice', so on so forth.