306 Switch Proxy
A reserved, unused status code that no longer carries any meaning.
What it means
HTTP 306 was used in an early draft of the HTTP specification but the meaning it had then was dropped. The code number is now reserved and carries no defined behaviour. It exists only so the number is not reassigned to something new.
When it happens
It does not happen in practice. No server should send it and no client acts on it; it lives on purely as a reserved slot in the status-code registry.
How to fix it
- Nothing to do — 306 is reserved and unused, so you will not encounter it legitimately.
- If something emits 306, treat it as a server bug and replace it with a valid status.
SEO impact
None. It is a reserved code with no behaviour, so it never appears in real crawling or indexing.
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Related codes
The resource has permanently moved to a new URL.
302 FoundThe resource is temporarily at a different URL.
303 See OtherThe response to the request can be found at another URL using a GET request.
304 Not ModifiedThe cached version of the resource is still valid, so no body is sent.
305 Use ProxyA deprecated code telling the client it must reach the resource through a specified proxy.
307 Temporary RedirectA temporary redirect that preserves the original request method.
Related guides
A plain-English primer on HTTP status codes for SEOs: what the 2xx, 3xx, 4xx, and 5xx families mean, which ones affect rankings, and the codes worth knowing.
How to find and fix broken linksA practical walkthrough for finding broken links on your site, working out why each one breaks, and fixing them so visitors and crawlers stop hitting dead ends.