ERC721: caller is not token owner or approved?

To address the issue of "ERC721: caller is not token owner or approved," we can create a step-by-step guide that not only explains the error but also integrates the function of Bulk Token Sender, a tool designed for transferring or airdropping tokens or NFTs in bulk. The guide will begin with an introduction to Bulk Token Sender and its relevance in the context of ERC721 tokens.

Introduction to Bulk Token Sender

Bulk Token Sender is a platform that facilitates the efficient transfer or airdrop of tokens, including NFTs (Non-Fungible Tokens) that adhere to the ERC721 standard. This tool is particularly useful for projects or individuals looking to distribute tokens en masse to multiple recipients, simplifying what would otherwise be a labor-intensive process. You can find more about this tool at Bulk Token Sender.

Step-by-Step Guide: Resolving "ERC721: caller is not token owner or approved" Error

Step 1: Understanding the Error

  • Error Explanation: The "ERC721: caller is not token owner or approved" error occurs when a transaction is attempted by an account that neither owns the token in question nor has been given approval to act on behalf of the owner.

Step 2: Verify Token Ownership

  • Action: Check if the account trying to transfer the token is indeed the owner. This can be done by querying the ownership details on the blockchain using tools like Etherscan.

Step 3: Confirm Approval Status

  • Action: If the account is not the owner, verify if it has been approved by the token owner to manage the token. Approval is a necessary step for third-party transfers.

Step 4: Granting Approval

  • Action: If approval has not been granted, the actual token owner needs to authorize the third-party account. This is typically done through a transaction that grants approval to the account attempting the transfer.

Step 5: Utilizing Bulk Token Sender

  • Action: Once approval is in place, Bulk Token Sender can be used to facilitate the transfer or airdrop of the ERC721 tokens. Ensure that the sender account is either the owner or has been approved by the owner.

Step 6: Executing the Transfer

  • Action: With Bulk Token Sender, input the details of the recipients and the specific tokens to be transferred. Follow the platform's process to execute the bulk transfer.

Step 7: Confirming Transaction Completion

  • Action: After initiating the transfer, monitor the transaction status. Use blockchain explorers to verify that the tokens have reached their intended recipients.


Resolving the "ERC721: caller is not token owner or approved" error typically involves ensuring proper ownership or approval before attempting a transfer. Bulk Token Sender streamlines the process for bulk transactions once these prerequisites are met, making it an invaluable tool for large-scale token distributions.

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