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400 Bad Request

Document v1 · published by Koskamo · updated 2026-10-04

Original source

HTTP 400 Bad Request is a 4xx client error status code in the IANA HTTP Status Code Registry.

  • Code: 400
  • Reason phrase: Bad Request
  • Class: 4xx (Client Error)
  • Defined in: RFC 9110, Section 15.5.1

Source and provenance

Original source
www.iana.org
Published on Koskamo by
Koskamo
Citation version
Document v1
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IANA HTTP Status Code Registry (iana.org/assignments/http-status-codes); registry data reproduced verbatim with references

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The IANA registry identifies the registered status code and its specification. Follow that specification for protocol behavior; individual applications can add their own response details.

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Version history

  1. Published by Koskamo

    Version 1