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306

Unused

3xx Redirection

.md

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

305

Use Proxy

This is an old HTTP idea that said, 'Use this proxy instead,' but modern systems should not rely on it.

307

Temporary Redirect

Go to this other address for now, and send the exact same kind of request there.