{
  "id": "communication/http-431-request-header-fields-too-large",
  "signature": "HTTP/1.1 431 Request Header Fields Too Large",
  "signature_zh": "HTTP/1.1 431 请求头字段过大",
  "regex": "431 Request Header Fields Too Large",
  "domain": "communication",
  "category": "resource_error",
  "subcategory": null,
  "root_cause": "The total size of HTTP request headers exceeds the server's configured limit (typically 8 KB to 16 KB).",
  "root_cause_type": "generic",
  "root_cause_zh": "HTTP请求头的总大小超过了服务器的配置限制（通常为8 KB到16 KB）。",
  "versions": [
    {
      "version": "nginx 1.26.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "Apache HTTP Server 2.4.59",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "Node.js 22.0.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "Increase server memory or CPU",
      "why_fails": "The error is a hard limit on header size, not a resource shortage; memory increase does not affect the limit.",
      "fail_rate": 0.9,
      "condition": "",
      "sources": []
    },
    {
      "action": "Disable all security modules or firewalls",
      "why_fails": "Most security tools do not cause this error; disabling them may expose the server without fixing the header size issue.",
      "fail_rate": 0.5,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "Increase the server's request header buffer size. For Nginx: 'large_client_header_buffers 4 32k;' in http or server block. For Apache: 'LimitRequestFieldSize 16380' in httpd.conf.",
      "success_rate": 0.95,
      "how": "Increase the server's request header buffer size. For Nginx: 'large_client_header_buffers 4 32k;' in http or server block. For Apache: 'LimitRequestFieldSize 16380' in httpd.conf.",
      "condition": "",
      "sources": []
    },
    {
      "action": "Reduce cookie sizes or move large state to server-side sessions. Example in Express.js: app.use(session({ store: new RedisStore(), cookie: { maxAge: 60000 } })) — store session data server-side instead of in cookies.",
      "success_rate": 0.85,
      "how": "Reduce cookie sizes or move large state to server-side sessions. Example in Express.js: app.use(session({ store: new RedisStore(), cookie: { maxAge: 60000 } })) — store session data server-side instead of in cookies.",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [
    "Increase the server's request header buffer size. For Nginx: 'large_client_header_buffers 4 32k;' in http or server block. For Apache: 'LimitRequestFieldSize 16380' in httpd.conf.",
    "Reduce cookie sizes or move large state to server-side sessions. Example in Express.js: app.use(session({ store: new RedisStore(), cookie: { maxAge: 60000 } })) — store session data server-side instead of in cookies."
  ],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": "https://httpwg.org/specs/rfc6585.html#status-431",
  "official_doc_section": null,
  "error_code": "431",
  "verification_tier": "ai_generated",
  "confidence": 0.9,
  "fix_success_rate": 0.9,
  "resolvable": "true",
  "first_seen": "2024-06-30",
  "last_confirmed": "2024-06-01",
  "last_updated": "2024-06-01",
  "evidence_count": 1,
  "tags": [],
  "locale": "en",
  "aliases": []
}