404 Not Found
Meaning
The server can't find the requested resource. This response code indicates that the server itself does not recognize the request path or resource.
When to Use
When the requested URL is not valid on the server or the resource has been removed and the server wants to pretend it doesn't exist. It’s a generic response for an unavailable resource.
Example
GET /api/items/999 returns 404 Not Found if item 999 does not exist on the server.
When Not to Use
Do not use if the resource is forbidden to the user but exists (in that case, 403 could be used depending on your design). Also, do not use for server errors or invalid request formats.
Source
RFC 9110