[CLOSED] OpenSeaClone - Fail with error 'ERC721: transfer caller is not owner nor approved'

Dear Support team,

I am having this error,
Fail with error ‘ERC721: transfer caller is not owner nor approved’
My contract address is:

I just passed the 1:01 time in the youtube tutorial.

Hope you can guide or help me in resolving the error.


You may have to give more info than a contract address.
Does the wallet address that tries to make the transfer own the nft or it is allowed to transfer it?

I bought the nft using my metamask from an anonymous user in mumbai polygon testnet,

Buying was successful, so now I owned it. Then I deployed my smart contract and sold the nft by clicking the sell button. Then the error came.

Can you check what is the owner of that token id? Just to be sure.

How do i check the owner of the token id? If you can please guide me, it will be highly appreciated. Thanks!

My metamask address:

Created by:

Owned by:


Can you post a screenshot of your wallet address authenticated with the app. What is the NFT contract address and tokenId you are trying to sell? Post a screenshot of this as well on the OpenSea clone app.

You can check ownership directly on the contract - if it’s verified on the chain explorer, you can check it on there (ownerOf).

Dear Glad,

I captured screenshots of my process. I cannot find the (ownerOf) on the contract, maybe because it failed, is that assumption valid?
These are some of the details:

NFT Contract address:

Token Id:

polygon mumbai testnet

deployed smart contract address:

metamask address:

transaction id:



Yes it looks like you have ownership of that NFT - everything looks fine there. Check this thread for another user who got this error and updates on it. Looks like you have to use approve first in the app - I don’t think it’s covered in the tutorial. Since it looks like you’re testing directly with Remix, it wouldn’t be obvious.