306

Unused

3xx Redirection

ELI5

This number exists in the HTTP list, but it does not mean anything you should use in a real app today.

Server perspective

Do not emit 306; it is reserved and has no defined modern behavior.

When to use

  • Keep 306 only as reference material in documentation
  • Choose a real standard status code instead of inventing meaning for 306
  • When documenting historical or reserved HTTP status codes
  • When explaining that not every number in the status code range is an active feature

How to respond

  • Audit any code path that returns 306 because it likely indicates a bug, placeholder, or undocumented custom behavior
  • Map the response to a defined HTTP status that matches the actual semantics

Headers to consider

  • No status-specific header is defined because 306 has no active modern semantics.

Response body

  • There is no defined response body contract for 306 because there is no active status semantics to implement

Server-side pitfalls

  • Do not use 306 as an internal shortcut hoping clients will understand it
  • Do not confuse 'reserved' with 'safe to repurpose'
  • Any real redirect, cache, or application response
  • Custom product semantics that should instead use a defined standard or documented vendor-specific contract

Examples

Reading an HTTP status code reference

Request:GET https://api.example.test/status/306
Response:306 Unused

The useful lesson is that clients should not build product logic around it.

References

Related Status Codes