Error - Base Chain (L2)

Support Contracts
1

Hello, I developed a simple ERC721 contrat throught OpenZeppelin on the new Coinbase L2, the Base chain but when I try to verify my contract I see this " Error! Unable to generate Contract ByteCode and ABI (General Exception, unable to get compiled [bytecode])"

I made some researches here and found some solutions for BNB chain and Ethereum but I am a newbie and I have no idea on how to proceed. Also I have a chromebook laptop, could it be a problem? Thanks in advance and kind regards!

2

Please share details (how, where, etc).

3

thanks for your answer (and your time)! I developed it almost 48h ago and tried to verify some minutes ago.

This is the contract and basescan seems not recognizing the "@openzeppelin" wording

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

import "@openzeppelin/contracts@4.9.3/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts@4.9.3/access/Ownable.sol";

contract BasedBases is ERC721, Ownable {
constructor() ERC721("BasedBases", "BDBS") {}

function safeMint(address to, uint256 tokenId) public onlyOwner {
    _safeMint(to, tokenId);
}

}

4

You need to flatten the contract's code.

You can do this manually, by replacing every import statement with the actual code being imported.

Or there is possibly a 'flatten source code' button somewhere in there (again - you haven't mentioned what platform you're using in order to verify your contract - etherscan, remix, etc - so it's a bit hard to say for sure).

5

Alright, thank you, I flattened it throught remix.. should I deploy it again?

6

No, flattening the code doesn't change anything in the actual bytecode.

The sole purpose of this flattening is in order to able to verify the contract.

7

Thank you barakman! I tried verifying it buuuut still go an error:

Error! Unable to generate Contract ByteCode and ABI
Found the following ContractName(s) in source code : Address , BasedBases , Context , ERC165 , ERC721 , IERC165 , IERC721 , IERC721Metadata , IERC721Receiver , Math , Ownable , SignedMath , Strings
But we were unable to locate a matching bytecode (err_code_2)

8

UPDATE: just found the (viral) error: the license

I followed a tutorial where the guy advised to select "no license" but I remember I always selected "MIT license" when I created any contract.

9

You need to do this recursively of course (i.e., keep replacing every import statement until there are none left).

10

Alright, will do it! Thanks for your precious help!

1 Like