This is the issue: ParserError: Source "@openzeppelin/contracts/access/Ownable.sol" not found: File import callback not supported. Showing a picture below. It's on bscscan between to verify. The error says it is trying to open a file with "@openzeppelin/contracts/..." and it can't find it. The thing is, how do I make it so it can find it? If that would be the case.

This is my contract (changed the token name for security reasons):

pragma solidity ^0.8.0;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol";

contract secret is ERC20 { constructor(uint256 initialsupply) public ERC20 ("secret", "secret") { _mint(msg.sender, initialsupply); } }

And when i verify it on bscscan i keep getting this. I have actually not much idea what to do now to fix this issue, would be really great if someone could give me an advice to solve this issue.

This is the issue I'm getting

2 Answers 2


Check out this page https://docs.openzeppelin.com/contracts/4.x/

First you do: $ npm install @openzeppelin/contracts

And then import ERC20.sol like: import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

  • Thank you for the advice, this is much what I thought in the first place, but this may sound stupid but would you give advice on how to install it in the first place, if it's on the remix, is it intended to deploy the token again? Myself, I don't think so. Basically, how do I install $ npm install @openzeppelin/contracts, is it on the remix? If so how can I do it? Or not Remix, how do I do it? This is the only problem I have @Severin. Very much thankful for your support otherwise.
    – Feynman
    Nov 28, 2021 at 0:12

If you are deploying through remix after importing OZ contracts, you need to flatten them in order to verify : https://forum.openzeppelin.com/t/verify-erc20-token-on-etherscan-that-was-deployed-through-remix-step-by-step-guide/9051

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