{
  "id": "communication/grpc-unavailable-no-route-to-host",
  "signature": "grpc::UNAVAILABLE: No route to host on connection attempt to remote endpoint",
  "signature_zh": "grpc::UNAVAILABLE：连接远程端点时无到达主机的路由",
  "regex": "grpc::UNAVAILABLE:\\s+No\\s+route\\s+to\\s+host",
  "domain": "communication",
  "category": "network_error",
  "subcategory": null,
  "root_cause": "gRPC client fails to establish TCP connection because the target IP address is unreachable due to network partition, firewall blocking, or incorrect DNS resolution.",
  "root_cause_type": "generic",
  "root_cause_zh": "gRPC 客户端无法建立 TCP 连接，因为目标 IP 地址由于网络分区、防火墙阻止或 DNS 解析错误而不可达。",
  "versions": [
    {
      "version": "gRPC 1.45.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "gRPC 1.50.2",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "gRPC 1.56.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "",
      "why_fails": "Increasing gRPC client timeout (e.g., setting 'grpc.timeout' to 60s) only delays failure; the underlying network issue persists.",
      "fail_rate": 0.8,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Disabling TLS verification ('GRPC_SSL_CIPHER_SUITES=ALL') does not resolve routing issues and introduces security vulnerabilities.",
      "fail_rate": 0.95,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Retrying with exponential backoff (e.g., using gRPC retry policy) may mask the issue temporarily but doesn't fix the route, leading to eventual timeout.",
      "fail_rate": 0.7,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "Verify network connectivity using 'ping' and 'traceroute' to the target host: ensure the IP address is reachable and no intermediate hops are dropping packets. Then fix DNS if needed by updating /etc/hosts or DNS server records.",
      "success_rate": 0.9,
      "how": "Verify network connectivity using 'ping' and 'traceroute' to the target host: ensure the IP address is reachable and no intermediate hops are dropping packets. Then fix DNS if needed by updating /etc/hosts or DNS server records.",
      "condition": "",
      "sources": []
    },
    {
      "action": "Check firewall rules on both client and server: ensure the gRPC port (default 50051) is open. Use 'iptables -L' or 'ufw status' to verify, and add allow rules if blocked.",
      "success_rate": 0.85,
      "how": "Check firewall rules on both client and server: ensure the gRPC port (default 50051) is open. Use 'iptables -L' or 'ufw status' to verify, and add allow rules if blocked.",
      "condition": "",
      "sources": []
    },
    {
      "action": "If using Kubernetes, verify network policies and service endpoints: 'kubectl get endpoints <service-name>' to ensure pods are correctly targeted, and check for misconfigured network policies blocking cross-namespace traffic.",
      "success_rate": 0.8,
      "how": "If using Kubernetes, verify network policies and service endpoints: 'kubectl get endpoints <service-name>' to ensure pods are correctly targeted, and check for misconfigured network policies blocking cross-namespace traffic.",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [
    "Verify network connectivity using 'ping' and 'traceroute' to the target host: ensure the IP address is reachable and no intermediate hops are dropping packets. Then fix DNS if needed by updating /etc/hosts or DNS server records.",
    "Check firewall rules on both client and server: ensure the gRPC port (default 50051) is open. Use 'iptables -L' or 'ufw status' to verify, and add allow rules if blocked.",
    "If using Kubernetes, verify network policies and service endpoints: 'kubectl get endpoints <service-name>' to ensure pods are correctly targeted, and check for misconfigured network policies blocking cross-namespace traffic."
  ],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": "https://grpc.io/docs/guides/error-codes/",
  "official_doc_section": null,
  "error_code": "UNAVAILABLE",
  "verification_tier": "ai_generated",
  "confidence": 0.88,
  "fix_success_rate": 0.86,
  "resolvable": "true",
  "first_seen": "2024-01-10",
  "last_confirmed": "2024-06-01",
  "last_updated": "2024-06-01",
  "evidence_count": 1,
  "tags": [],
  "locale": "en",
  "aliases": []
}