ERC-404 is an Ethereum token standard that governs how token smart contracts respond to invalid function calls by implementing the tokenNotFound function, similar to the HTTP 404 status code on websites.

ERC-404 was proposed by Miguel Angel Rodriguez in September 2022 to make token smart contracts on Ethereum more robust in handling incorrect or unrecognized function calls. This standard is inspired by the status code and error message mechanisms of the HTTP protocol.

By adopting ERC-404, when there is an invalid token function call, the smart contract will call the predefined tokenNotFound function to return an appropriate error message to the user. This prevents solidity exceptions from being thrown and tokens from getting trapped in the contract due to incorrect function calls.

ERC-404 is compatible with Ethereum fungible token standards, such as ERC-20. The goal of this standard is for token smart contracts to be more robust and informative in handling errors.

Examples of ERC-404 usage in a sentence

“After adopting ERC-404, our DeFi applications became more robust and informative when users incorrectly called token functions.”

“By implementing the token NotFound function of the ERC-404 standard, our token smart contract can return appropriate error messages to users.”

“ERC-404 was inspired by HTTP status codes familiar on the web to create a standard for good error handling on Ethereum tokens.”

Source:

https://medium.com/@themintland/what-is-erc-404-a-guide-to-the-new-standard-in-nfts-e42461d844e1