I'm trying to verify a simple contract. The contract is already deployed on the Ropsten network.

import "@openzeppelin/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract Tress is ERC20, AccessControl {
    bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
    bytes32 public constant BURNER_ROLE = keccak256("BURNER_ROLE");

    constructor() public ERC20("TRESS", "TRS") {
        // Grant the contract deployer the default admin role: it will be able
        // to grant and revoke any roles
        _setupRole(DEFAULT_ADMIN_ROLE, msg.sender);

    function mint(address to, uint256 amount) public {
        require(hasRole(MINTER_ROLE, msg.sender), "Caller is not a minter");
        _mint(to, amount);

    function burn(address from, uint256 amount) public {
        require(hasRole(BURNER_ROLE, msg.sender), "Caller is not a burner");
        _burn(from, amount);

But it doesn't work for me. It throws me the following error. enter image description here

I appreciate any help


By looking on the errors, there seems to be a file system problem as the command is not seeing the contract Tress.sol.(Can you give more details?).

Errors during verifying, can also occur if you delete the build directory after your deployment.

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