问在Etherscan上验证/发布智能契约

EN

npx hardhat clean 
npx hardhat verify --network rinkeby 0xDDeE39Ae632760906d273B450493405Dc3C455Fe "ipfs://QmX6MjxS5NsEFGe9WtKCskf5fhuifFvZ9Xi12tTBYPjEiH"

Compiling 17 files with 0.8.4
Compilation finished successfully
Compiling 1 file with 0.8.4
Successfully submitted source code for contract
contracts/NFTCollectible.sol:NFTCollectible at 0xDDeE39Ae632760906d273B450493405Dc3C455Fe
for verification on Etherscan. Waiting for verification result...

Error in plugin @nomiclabs/hardhat-etherscan: The contract verification failed.
Reason: Fail - Unable to verify

require("@nomiclabs/hardhat-waffle");
require("@nomiclabs/hardhat-etherscan");
require('dotenv').config();

const { API_URL, PRIVATE_KEY, ETHERSCAN_API } = process.env;

// This is a sample Hardhat task. To learn how to create your own go to
// https://hardhat.org/guides/create-task.html
task("accounts", "Prints the list of accounts", async (taskArgs, hre) => {
  const accounts = await hre.ethers.getSigners();

  for (const account of accounts) {
    console.log(account.address);
  }
});

// You need to export an object to set up your config
// Go to https://hardhat.org/config/ to learn more

/**
 * @type import('hardhat/config').HardhatUserConfig
 */
module.exports = {
  solidity: "0.8.4",
  defaultNetwork: "rinkeby",
  networks: {
    rinkeby: {
      url: API_URL,
      accounts: [PRIVATE_KEY]
    }
  },
  etherscan: {
    apiKey: ETHERSCAN_API
  }
};

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";

contract NFTCollectible is ERC721Enumerable, Ownable {
    using SafeMath for uint256;
    using Counters for Counters.Counter;

    Counters.Counter private _tokenIds;

    uint256 public constant MAX_SUPPLY = 100;
    uint256 public constant PRICE = 0.01 ether;
    uint256 public constant MAX_PER_MINT = 5;

    string public baseTokenURI;

    constructor(string memory baseURI) ERC721("NFT Collectible", "NFTC") {
        setBaseURI(baseURI);
    }

    function reserveNFTs() public onlyOwner {
        uint256 totalMinted = _tokenIds.current();
        require(totalMinted.add(10) < MAX_SUPPLY, "Not enough NFTs");
        for (uint256 i = 0; i < 10; i++) {
            _mintSingleNFT();
        }
    }

function _baseURI() internal view virtual override returns (string memory) {
    return baseTokenURI;
}

function setBaseURI(string memory _baseTokenURI) public onlyOwner {
    baseTokenURI = _baseTokenURI;
}

function mintNFTs(uint256 _count) public payable {
    uint256 totalMinted = _tokenIds.current();
    require(totalMinted.add(_count) <= MAX_SUPPLY, "Not enough NFTs!");
    require(
        _count > 0 && _count <= MAX_PER_MINT,
        "Cannot mint specified number of NFTs."
    );
    require(
        msg.value >= PRICE.mul(_count),
        "Not enough ether to purchase NFTs."
    );
    for (uint256 i = 0; i < _count; i++) {
        _mintSingleNFT();
    }
}

function _mintSingleNFT() private {
    uint256 newTokenID = _tokenIds.current();
    _safeMint(msg.sender, newTokenID);
    _tokenIds.increment();
}

function tokensOfOwner(address _owner)
    external
    view
    returns (uint256[] memory)
{
    uint256 tokenCount = balanceOf(_owner);
    uint256[] memory tokensId = new uint256[](tokenCount);
    for (uint256 i = 0; i < tokenCount; i++) {
        tokensId[i] = tokenOfOwnerByIndex(_owner, i);
    }

    return tokensId;
}

function withdraw() public payable onlyOwner {
    uint256 balance = address(this).balance;
    require(balance > 0, "No ether left to withdraw");
    (bool success, ) = (msg.sender).call{value: balance}("");
    require(success, "Transfer failed.");
}