405 Method Not Allowed

4xx Client Error RFC 9110

That verb doesn't work here.

What 405 Method Not Allowed means {#what}

The HTTP method you used (GET, POST, DELETE, etc.) is not supported by this endpoint. The server must include an Allow header listing the supported methods.

When you’ll see a 405 {#when}

Sending a DELETE to a read-only endpoint
POSTing to a URL that only accepts GET
Any mismatch between method and route

When to use 405 {#use}

Always include the Allow header (e.g., Allow: GET, POST)

Don't confuse 405

404 the route doesn't exist at all; 405 means it exists but not for that method 501 the method isn't supported by the server at all, not just this route