HTTP 401 Unauthorized vs 405 Method Not Allowed
Both HTTP 401 (Unauthorized) and 405 (Method Not Allowed) belong to the 4xx Client Error category. 401 indicates that the request requires user authentication. The response includes a WWW-Authenticate header indicating the authentication scheme. Meanwhile, 405 means that the HTTP method is not allowed for the requested resource. The response includes an Allow header listing valid methods.
Description
The request requires user authentication. The response includes a WWW-Authenticate header indicating the authentication scheme.
When You See It
When accessing a protected resource without credentials or with expired tokens.
How to Fix
Include valid authentication credentials (API key, Bearer token, Basic auth) in the Authorization header.
Description
The HTTP method is not allowed for the requested resource. The response includes an Allow header listing valid methods.
When You See It
When sending POST to a read-only endpoint, or DELETE to a non-deletable resource.
How to Fix
Check the Allow response header for supported methods. Use the correct HTTP method.
Key Differences
HTTP 401: The request requires user authentication. The response includes a WWW-Authenticate header indicating the authentication scheme.
HTTP 405: The HTTP method is not allowed for the requested resource. The response includes an Allow header listing valid methods.
You encounter 401 when when accessing a protected resource without credentials or with expired tokens.
You encounter 405 when when sending POST to a read-only endpoint, or DELETE to a non-deletable resource.
When to Use Which
For 401 (Unauthorized): Include valid authentication credentials (API key, Bearer token, Basic auth) in the Authorization header. For 405 (Method Not Allowed): Check the Allow response header for supported methods. Use the correct HTTP method.