Transaction failed-CALL_EXCEPTION

Question

I deployed smart contract to testnet and i got error can someone help me debug this

Code:

pragma solidity ^0.8.20;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";

interface IERC3156FlashBorrower {
    function onFlashLoan(
        address initiator,
        address token,
        uint256 amount,
        uint256 fee,
        bytes calldata data
    ) external returns (bytes32);
}

contract FlashBorrower2 is Context, ReentrancyGuard, IERC3156FlashBorrower {
    using SafeERC20 for IERC20;

    address private owner;
    uint256 public constant MAX_INT = type(uint256).max;
    address USDC = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;

    constructor() {
        owner = msg.sender;
    }

    modifier OnlyOwner() {
        require(msg.sender == owner);
        _;
    }

    function onFlashLoan(
        address initiator,
        address token,
        uint256 amount,
        uint256 fee,
        bytes calldata data
    ) external override nonReentrant returns (bytes32) {
        IERC20(token).approve(msg.sender, MAX_INT);
        uint256 amountOutExpected;
        uint256 amountOutExpected2;
        (amountOutExpected, amountOutExpected2) = abi.decode(
            data,
            (uint256, uint256)
        );
        address UNISWAP_ROUTER_ADDRESS = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D;
        address SUSHISWAP_ROUTER_ADDRESS = 0xd9e1cE17f2641f24aE83637ab66a2cca9C378B9F;

        IUniswapV2Router02 uniswapRouter = IUniswapV2Router02(
            UNISWAP_ROUTER_ADDRESS
        );
        IUniswapV2Router02 sushiSwapRouter = IUniswapV2Router02(
            SUSHISWAP_ROUTER_ADDRESS
        );

        address[] memory path = new address[](2);
        path[0] = token;
        path[1] = USDC;

        uniswapRouter.swapExactTokensForTokens(
            amount,
            amountOutExpected,
            path,
            address(this),
            block.timestamp
        );

        address[] memory path2 = new address[](2);
        path2[0] = USDC;
        path2[1] = token;

        sushiSwapRouter.swapExactTokensForTokens(
            IERC20(USDC).balanceOf(address(this)),
            amountOutExpected2,
            path2,
            address(this),
            block.timestamp
        );

        return keccak256("ERC3156FlashBorrower.onFlashLoan");
    }

    function withdrawWETH(address WETH) external OnlyOwner {
        require(
            IERC20(WETH).balanceOf(address(this)) > 0,
            "No funds to withdraw"
        );
        IERC20(WETH).transfer(owner, IERC20(WETH).balanceOf(address(this)));
    }
}

ERROR:

Error: transaction failed [ See: https://links.ethers.org/v5-errors-CALL_EXCEPTION ] (transactionHash="0x05b56cf7dde5495ec7ff5ed13bf1a64f45481e19c20fd948b69f56a0669e9a7d", transaction={"type":2,"chainId":11155111,"nonce":21,"maxPriorityFeePerGas":{"type":"BigNumber","hex":"0x010aaeb4f1"},"maxFeePerGas":{"type":"BigNumber","hex":"0x010aaeb4f1"},"gasPrice":null,"gasLimit":{"type":"BigNumber","hex":"0x017d7840"},"to":"0xD6011CC83d2Be6db63105574e230D8314307518e","value":{"type":"BigNumber","hex":"0x00"},"data":"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","accessList":[],"hash":"0x05b56cf7dde5495ec7ff5ed13bf1a64f45481e19c20fd948b69f56a0669e9a7d","v":0,"r":"0x820c7007b97f38ff6bae728d1a10e73f952520545193d186acd53bc6c4690502","s":"0x57dd20396db78e0ef5ea6711610a40fd7517f0203403483f1df94cae7835139d","from":"0x52E48123Dd1d3A2DbFcf60670D5d4d192Fd0bd78","confirmations":0}, receipt={"to":"0xD6011CC83d2Be6db63105574e230D8314307518e","from":"0x52E48123Dd1d3A2DbFcf60670D5d4d192Fd0bd78","contractAddress":null,"transactionIndex":8,"gasUsed":{"type":"BigNumber","hex":"0x7d7d"},"logsBloom":"0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000","blockHash":"0x45e6ea1c2bac4b5ce14fb7d44b41ed4efccb2cf829da5a673962e4b8c5f5be4d","transactionHash":"0x05b56cf7dde5495ec7ff5ed13bf1a64f45481e19c20fd948b69f56a0669e9a7d","logs":[],"blockNumber":4874132,"confirmations":1,"cumulativeGasUsed":{"type":"BigNumber","hex":"0x03885f"},"effectiveGasPrice":{"type":"BigNumber","hex":"0x010aaeb4f1"},"status":0,"type":2,"byzantium":true}, code=CALL_EXCEPTION, version=providers/5.7.2)
    at Logger.makeError (E:\TESTNETSANDWITCH\node_modules\@ethersproject\logger\src.ts\index.ts:269:28)
    at Logger.throwError (E:\TESTNETSANDWITCH\node_modules\@ethersproject\logger\src.ts\index.ts:281:20)
    at JsonRpcProvider.<anonymous> (E:\TESTNETSANDWITCH\node_modules\@ethersproject\providers\src.ts\base-provider.ts:1549:24)
    at step (E:\TESTNETSANDWITCH\node_modules\@ethersproject\providers\lib\base-provider.js:48:23)
    at Object.next (E:\TESTNETSANDWITCH\node_modules\@ethersproject\providers\lib\base-provider.js:29:53)
    at fulfilled (E:\TESTNETSANDWITCH\node_modules\@ethersproject\providers\lib\base-provider.js:20:58) {
  reason: 'transaction failed',
  code: 'CALL_EXCEPTION',
  transactionHash: '0x05b56cf7dde5495ec7ff5ed13bf1a64f45481e19c20fd948b69f56a0669e9a7d',
  transaction: {
    type: 2,
    chainId: 11155111,
    nonce: 21,
    maxPriorityFeePerGas: BigNumber { _hex: '0x010aaeb4f1', _isBigNumber: true },
    maxFeePerGas: BigNumber { _hex: '0x010aaeb4f1', _isBigNumber: true },
    gasPrice: null,
    gasLimit: BigNumber { _hex: '0x017d7840', _isBigNumber: true },
    to: '0xD6011CC83d2Be6db63105574e230D8314307518e',
    value: BigNumber { _hex: '0x00', _isBigNumber: true },
    data: '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',
    accessList: [],
    hash: '0x05b56cf7dde5495ec7ff5ed13bf1a64f45481e19c20fd948b69f56a0669e9a7d',
    v: 0,
    r: '0x820c7007b97f38ff6bae728d1a10e73f952520545193d186acd53bc6c4690502',
    s: '0x57dd20396db78e0ef5ea6711610a40fd7517f0203403483f1df94cae7835139d',
    from: '0x52E48123Dd1d3A2DbFcf60670D5d4d192Fd0bd78',
    confirmations: 0,
    wait: [Function (anonymous)]
  },
  receipt: {
    to: '0xD6011CC83d2Be6db63105574e230D8314307518e',
    from: '0x52E48123Dd1d3A2DbFcf60670D5d4d192Fd0bd78',
    contractAddress: null,
    transactionIndex: 8,
    gasUsed: BigNumber { _hex: '0x7d7d', _isBigNumber: true },
    logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',
    blockHash: '0x45e6ea1c2bac4b5ce14fb7d44b41ed4efccb2cf829da5a673962e4b8c5f5be4d',
    transactionHash: '0x05b56cf7dde5495ec7ff5ed13bf1a64f45481e19c20fd948b69f56a0669e9a7d',
    logs: [],
    blockNumber: 4874132,
    confirmations: 1,
    cumulativeGasUsed: BigNumber { _hex: '0x03885f', _isBigNumber: true },
    effectiveGasPrice: BigNumber { _hex: '0x010aaeb4f1', _isBigNumber: true },
    status: 0,
    type: 2,
    byzantium: true
  }
}

Answer 1

Looking at the transaction hash on Sepolia, it looks like you called onFlashLoan on your contract with the following parameters:

| # | Name      | Type    | Data                                       |
|---|-----------|---------|--------------------------------------------|
| 0 | initiator | address | 0xD6011CC83d2Be6db63105574e230D8314307518e |
| 1 | asset     | address | 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 |
| 2 | amount    | uint256 | 500000000000000000000                      |
| 3 | fee       | uint256 | 0                                          |
| 4 | data      | bytes   | 0x                                         |

In your code, you call approve on the asset (token) parameter. However, looking at the specified asset address, we see it's an EOA. No code, and no approve method exists. I think you simply put your arguments in incorrectly.