The Ultimate Guide to HTTP Status Codes (100–599)
A complete reference guide to all HTTP status codes from 100 to 599, with explanations and common use cases.
Feb 28, 2026
306
HTTP 306 Unused
3xx Redirection
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3xx Redirection
RFC 7231, Section 6.4.6
What is HTTP 306 Unused?
The 306 (Unused) status code was used in a previous version of HTTP/1.1 specification for Switch Proxy. It is no longer used and is reserved.
Usage Example
The 306 status code is reserved and unused. It should never be implemented or returned by servers. If you encounter it in client code, treat it as an unknown/unexpected response.
// 306 is reserved and unused - do not implementRelated Status Codes
Last updated: 17 Aug 2026