NotFoundError

NotFoundError is a type of error used in software to signal that a requested resource cannot be located. In web services, it commonly corresponds to the HTTP 404 Not Found status.

It can be raised or returned by server-side code when a client requests an entity by identifier or path that does not exist. The error typically includes a message and may include an identifier, path, or resource type, along with a status code and optional cause.

In practice, frameworks provide various implementations: some define a dedicated NotFoundError class; others use a generic error with an attached 404 status. Handling usually involves catching the error and generating an appropriate response, such as a 404 response with a human-readable message.

Domains include REST APIs, database queries, and filesystem operations. For example, a read operation for a non-existent record or file would trigger a NotFoundError. Differences across languages may affect how it is declared (checked vs unchecked exceptions) but the conceptual meaning remains.

Design considerations: keep error messages concise, avoid leaking sensitive details, provide enough context to identify the missing resource, and ensure consistent error shapes for clients.