Metadata not showing up for ERC-721 OpenSea NFT

Question

I made NFT's, following this tutorial

I deployed the smart contract via Remix to my Metamask on the Rinkeby Testnet. OpenSea detected the assets in my wallet after they were minted, but the pictures and metadata in the json files was not there. Here is my smart contract:

// SPDX-License-Identifier: MIT
pragma solidity ^ 0.8.10;

//import Open Zepplin contracts
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/ERC721.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Strings.sol";

contract NFT is ERC721 {
    uint256 private _tokenIds;
    
    constructor() ERC721("Name", "Symbol") {}
    
//use the mint function to create an NFT
    function mint() public returns (uint256) {
        _tokenIds += 1;
        _safeMint(msg.sender, _tokenIds);
        return _tokenIds;
    }
    
//in the function below include the CID of the JSON folder on IPFS
    function tokenURI(uint256 _tokenId) override public pure returns(string memory) {
        return string(
            abi.encodePacked(
                "ipfs://QmYiWynKnLwAPPEYdEhtPH5YhqKhq8wsnXZ6FKFBoi2G5t",
                Strings.toString(_tokenId),
                ".json"
            )
        );
    }
}

The ipfs URL contains the CID generated from the JSON files on Pinata. I am sure I did not use the jpeg CID. When I tried to debug my data via OpenSea's tool, I got the following:

HTTP 200 OK
Allow: OPTIONS, GET
Content-Type: application/json
Vary: Accept

{
    "valid": false,
    "token_uri": "https://ipfs.io/ipfs/QmYiWynKnLwAPPEYdEhtPH5YhqKhq8wsnXZ6FKFBoi2G5t/2.json",
    "errors": [
        "TokenUrl404ResponseException: Received 404 response for: https://ipfs.io/ipfs/QmYiWynKnLwAPPEYdEhtPH5YhqKhq8wsnXZ6FKFBoi2G5t/2.json"
    ]
}

Answer 1

man you are missing a slash /

pragma solidity ^ 0.8.10;

//import Open Zepplin contracts
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/utils/Strings.sol"; 
contract NFT is ERC721 {
    uint256 private _tokenIds;
    
    constructor() ERC721("Name", "Symbol") {}
    
//use the mint function to create an NFT
    function mint() public returns (uint256) {
        _tokenIds += 1;
        _safeMint(msg.sender, _tokenIds);
        return _tokenIds;
    }
    
//in the function below include the CID of the JSON folder on IPFS
    function tokenURI(uint256 _tokenId) override public pure returns(string memory) {
        return string(
            abi.encodePacked(
                "ipfs://QmYiWynKnLwAPPEYdEhtPH5YhqKhq8wsnXZ6FKFBoi2G5t/",
                Strings.toString(_tokenId),
                ".json"
            )
        );
    }
}

ipfs://QmYiWynKnLwAPPEYdEhtPH5YhqKhq8wsnXZ6FKFBoi2G5t/0.json now uri will come correct

Answer 2

OpenSea sends the response "TokenUrl404ResponseException: Received 404 response for: https://ipfs.io/ipfs/QmYiWynKnLwAPPEYdEhtPH5YhqKhq8wsnXZ6FKFBoi2G5t/2.json" which means that it can't find that file.

If you paste the address in your browser you'll see that indeed the you can't access this link.

By removing the file name and going to the directory, you'll see that your file names are different - token number 2's file name is nft2.json. But your smart contract is returning "2.json" - that's a part of the problem.

But even if you would link to nft2.json, actually all the files in that directory are empty. So something also went wrong in your upload to IPFS.

Answer 3

OpenSea seems to have issue parsing the .json extension. Try uploading without the extension, i.e. CID/1 instead of CID/1.json. Also, tokenURI needs a slash as mentioned in some of the other answers.