PancakeSwap Router Contract call: <UnrecognizedContract> Error: call revert exception

Question

I am using ethers.js, hardhat, and pancakeswaps router to run getAmountsOut(), but I am getting an error.

The error I get in the terminal is...

Error: call revert exception [ See: https://links.ethers.org/v5-errors-CALL_EXCEPTION ] (method="getAmountsOut(uint256,address[])", data="0x", errorArgs=null, errorName=null, errorSignature=null, reason=null, code=CALL_EXCEPTION, version=abi/5.7.0)

The error I get in the hardhat node is...

Contract call: <UnrecognizedContract>
From: 0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266
To: 0xeff92a263d31888d860bd50809a8d171709b7b1c

Error: Transaction reverted without a reason string
at <UnrecognizedContract>.<unknown> (0xeff92a263d31888d860bd50809a8d171709b7b1c)

This is the code I am currently working with...

const fetch = require('node-fetch');
const hre = require('hardhat');
const { ethers } = require("ethers");
const { ChainId, Fetcher} = require('@uniswap/sdk');


const WETH =  "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2";     //weth address
const router =  "0xEfF92A263d31888d860bD50809A8D171709b7b1c";   //uniswap v2 router address


const provider = new hre.ethers.providers.WebSocketProvider("ws://127.0.0.1:8545/");


const ME = "";    //pulls wallet from private key
const wallet = new hre.ethers.Wallet("");
const signer = wallet.connect(provider);

const routerContract = new hre.ethers.Contract(
    router,
    [
        'function getAmountsOut(uint amountIn, address[] memory path) public view returns (uint[] memory amounts)',
        'function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline) external payable returns (uint[] memory amounts)',
        'function swapExactTokensForETHSupportingFeeOnTransferTokens(uint amountIn,uint amountOutMin,address[] calldata path,address to,uint deadline) external'
     ],
    signer
);



//inputs: token address as a string and buy amount in ETH(1 = 1 ETH)
 async function purchaseToken(token_address,buyAmount) {


    const ETHAmountIn = hre.ethers.utils.parseUnits(buyAmount.toString(), 'ether');


    let amounts = await routerContract.getAmountsOut(ETHAmountIn, [WETH, token_address]);


    let amountOutMin = amounts[1].sub(amounts[1].div(10));

    
    const swapTx = await routerContract.swapExactETHForTokens(
        amountOutMin,
        [WETH, token_address],
        ME,
        Date.now() + 1000 * 60 * 10,
        {'value': ETHAmountIn, 'gasLimit': 900000, 'gasPrice': '0x22ECB25C00'}
    )


    let receipt = await swapTx.wait();
    console.log(receipt);
    
    return true;
}

I have tried the same code with uniswap v2 router but when I swap it with pancakes router I get these errors. Does anyone know what im doing wrong?

Answer 1

The issue you're facing might be due to two reasons:

• Your provider is pointing to a local network:

const provider = new hre.ethers.providers.WebSocketProvider("ws://127.0.0.1:8545/");

Make sure you connect to the correct network.

• You are using Uniswap SDK, which might not be fully compatible with PancakeSwap. I recommend using PancakeSwap SDK for better compatibility. You can find it here: https://github.com/pancakeswap/pancake-swap-sdk

By addressing these issues, your code should work correctly with PancakeSwap Router.