Solidity Interfaces : VM revert Error

Question

Im implementing a NFT Marketplace. Where I created Two contracts and an Interface. One contract is Tokens.sol and anotherone is MarketPlace.sol In Tokens Contract I Implemented functions like Minting and publishing operations and in Marketplace contract I handled buy and sell and other operations and in Interface I declared some getter functions and a minting function. All the getter functions are working fine but the Mint function is not working. It is throwwing an VM Revert Error. Here are the code snippets. Tokens.sol

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/token/ERC1155/extensions/ERC1155URIStorage.sol";

contract Token is ERC1155URIStorage {
 using Counters for Counters.Counter;
 Counters.Counter private _tokenIds;
function createAd(string memory _uri,address receiver) external payable{
    _tokenIds.increment();
    uint256 newTokenId = _tokenIds.current();
    _mint(receiver, newTokenId, 1, "");
    _setURI(newTokenId, _uri);
    Ad memory newAd = Ad(
        newTokenId,
        _uri,
        receiver,
        new address[](0),
        false,
        0,
        0
    );
    ads[newTokenId] = newAd;
    emit AdCreated(newTokenId, _uri, receiver);
}

Itoken.sol

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface ITokens {
    struct Video {
        uint id;
        string URI;
        uint256 price;
        uint256 views;
        uint256 likes;
        uint256 dislikes;
        uint256 shares;
        uint256 comments;
        uint256 total;
        uint256 timestamp;
    }

function getVideo(uint _id) external view returns (Video memory);


function createAd(string memory _uri,address receiver) external payable;
}

marketplace.sol

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./ITokens.sol";

contract MarketPlace  {
    ITokens private _tokens;

    constructor(address tokens) {
        _tokens = ITokens(tokens);
    }

    function getVideo(uint _id) external view returns (ITokens.Video memory) {
        return _tokens.getVideo(_id);
    }
    
    function mint() public returns(bool ){
        _tokens.createAd("kakakak");
        return true;
    }
}

and the error is

transact to MarketPlace.mint errored: VM error: revert.

revert
    The transaction has been reverted to the initial state.
Note: The called function should be payable if you send value and the value you send `should be less than your current balance.`
Debug the transaction to get more information.

Answer 1

As the error is saying, the createAd() method defined in the ITokens interface is a payable one, thus you need to also mark the mint() method defined in the MarketPlace contract as payable.

That's because you're calling the _tokens.createAd("kakakak"); method from the mint()one which needs to be able to receive value in order to pass it to the targeted one.

Update the mint() method as follows:

function mint() public payable returns(bool ){
    _tokens.createAd("kakakak");
    return true;
}