{
  "id": "nginx/upstream-sent-http-1-0",
  "signature": "upstream sent HTTP/1.0 response while reading response header from upstream, client: 192.168.1.10",
  "signature_zh": "上游返回HTTP/1.0响应",
  "regex": "upstream sent HTTP/1\\.0 response while reading response header from upstream",
  "domain": "nginx",
  "category": "protocol_error",
  "subcategory": null,
  "root_cause": "Upstream server sent an HTTP/1.0 response when nginx expected HTTP/1.1 or higher, often due to a misconfigured backend or legacy application.",
  "root_cause_type": "generic",
  "root_cause_zh": "上游服务器发送了HTTP/1.0响应，而nginx期望HTTP/1.1或更高版本，通常由后端配置错误或遗留应用引起。",
  "versions": [
    {
      "version": "nginx 1.18.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "nginx 1.20.2",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "nginx 1.24.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "",
      "why_fails": "This forces nginx to speak HTTP/1.0 to upstream, but may cause other issues like missing chunked transfer encoding; the error remains if upstream still sends HTTP/1.0.",
      "fail_rate": 0.6,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Buffering does not change the protocol version; the error will still appear in logs and may cause intermittent failures.",
      "fail_rate": 0.75,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Restarting does not change the protocol version the upstream uses; misconfiguration persists.",
      "fail_rate": 0.85,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "Configure upstream to use HTTP/1.1 (e.g., for Node.js: set 'keepAliveTimeout' and HTTP version; for Apache: ensure 'SetEnv nokeepalive 0' is not set).",
      "success_rate": 0.85,
      "how": "Configure upstream to use HTTP/1.1 (e.g., for Node.js: set 'keepAliveTimeout' and HTTP version; for Apache: ensure 'SetEnv nokeepalive 0' is not set).",
      "condition": "",
      "sources": []
    },
    {
      "action": "In nginx, set proxy_http_version to 1.1 and ensure proxy_set_header Connection ''; to handle keep-alive properly:\nproxy_http_version 1.1;\nproxy_set_header Connection '';",
      "success_rate": 0.75,
      "how": "In nginx, set proxy_http_version to 1.1 and ensure proxy_set_header Connection ''; to handle keep-alive properly:\nproxy_http_version 1.1;\nproxy_set_header Connection '';",
      "condition": "",
      "sources": []
    },
    {
      "action": "If upstream is a legacy system that only supports HTTP/1.0, consider using a middleware proxy that upgrades the protocol.",
      "success_rate": 0.4,
      "how": "If upstream is a legacy system that only supports HTTP/1.0, consider using a middleware proxy that upgrades the protocol.",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [
    "Configure upstream to use HTTP/1.1 (e.g., for Node.js: set 'keepAliveTimeout' and HTTP version; for Apache: ensure 'SetEnv nokeepalive 0' is not set).",
    "In nginx, set proxy_http_version to 1.1 and ensure proxy_set_header Connection ''; to handle keep-alive properly:\nproxy_http_version 1.1;\nproxy_set_header Connection '';",
    "If upstream is a legacy system that only supports HTTP/1.0, consider using a middleware proxy that upgrades the protocol."
  ],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": "https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_http_version",
  "official_doc_section": null,
  "error_code": null,
  "verification_tier": "ai_generated",
  "confidence": 0.83,
  "fix_success_rate": 0.8,
  "resolvable": "true",
  "first_seen": "2023-06-20",
  "last_confirmed": "2024-06-01",
  "last_updated": "2024-06-01",
  "evidence_count": 1,
  "tags": [],
  "locale": "en",
  "aliases": []
}