306 Unused
It was defined in an earlier draft of HTTP (as "Switch Proxy"), was never adopted, and is now permanently reserved in the IANA registry.
306 is a reserved status code that is no longer used.
What HTTP 306 Unused Means
306 is a reserved status code that is no longer used.
It was defined in an earlier draft of HTTP (as "Switch Proxy"), was never adopted, and is now permanently reserved in the IANA registry.
Common Causes
- Should never be sent by a modern, standards-compliant server
- Legacy, experimental, or buggy software reusing the number
- A custom application inventing its own meaning for 306
What Visitors Should Do
- Nothing to fix on your side - if you see 306, the server is misbehaving
- Report it to the site owner if a page fails to load
Notes for Developers
- Never send 306 - clients do not know how to handle it
- Use 307 or 308 for redirects that must keep the request method
- Configure proxies through client or network settings, not via status codes
Frequently Asked Questions
What does HTTP 306 Unused mean?
It was defined in an earlier draft of HTTP (as "Switch Proxy"), was never adopted, and is now permanently reserved in the IANA registry. In short: 306 is a reserved status code that is no longer used.
How should I handle an HTTP 306 Unused response?
Never send 306 - clients do not know how to handle it. Use 307 or 308 for redirects that must keep the request method. Configure proxies through client or network settings, not via status codes.
Official Specification
The 306 Unused status code is reserved in RFC 9110 Section 15.4.7.