405 Method Not Allowed means the server knows the request method, but the target resource does not support it. The response must include an Allow header that lists the methods the resource does support, for example Allow: GET, HEAD, OPTIONS.
Typical cases are a POST to a static file, a DELETE on a read-only API resource, or a GET on an endpoint that only accepts form posts. If the server does not recognise the method at all, 501 Not Implemented is the right answer instead.
A 405 is heuristically cacheable.
Example response
HTTP/1.1 405 Method Not Allowed
Date: Fri, 06 Nov 2026 10:15:32 GMT
Allow: GET, HEAD, OPTIONS
Content-Type: application/json
Content-Length: 30
{"error":"method_not_allowed"}SEO and redirect checking
A 405 for normal GET requests is a 4xx error and prevents indexing. More often the problem shows up with other methods: some servers and frameworks answer HEAD with 405, which confuses link checkers and monitoring tools that use HEAD to save bandwidth. If a check with the method set to HEAD returns 405 while GET returns 200, the server mishandles HEAD, even though HTTP requires general-purpose servers to support it.
Common causes and use cases
- A form or API client posts to a URL that only serves static content; nginx answers such requests with "405 Not Allowed".
- A framework route only defines
GET, soHEAD,POSTorPUTare rejected. - A redirect kept the method: after a 307 or 308, a
POSTstays aPOSTand may land on a page that only acceptsGET. - WebDAV or other methods are disabled in the server configuration.