Unavailable dotnet network_error ai_generated true

Grpc.Core.RpcException: Status(StatusCode="Unavailable", Detail="failed to connect to all addresses; last error: UNKNOWN: ipv4:192.168.1.1:443: No connection could be made because the target machine actively refused it.")

ID: dotnet/grpc-unavailable-connectivity

Also available as: JSON · Markdown · 中文
85%Fix Rate
85%Confidence
1Evidence
2023-04-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
net6.0 active — — —
net7.0 active — — —
net8.0 active — — —
net9.0 active — — —

Root Cause

The gRPC client cannot reach the server because the server is not running, the port is blocked by a firewall, or the endpoint address is incorrect.

generic

中文

gRPC 客户端无法到达服务器，因为服务器未运行、端口被防火墙阻止或端点地址不正确。

Official Documentation

https://learn.microsoft.com/en-us/aspnet/core/grpc/troubleshoot?view=aspnetcore-8.0

Workarounds

  1. 90% success Verify the server is running and listening on the expected port. Use 'netstat -an | findstr :443' (Windows) or 'ss -tuln | grep 443' (Linux) to check. Restart the gRPC server service if needed. 
    Verify the server is running and listening on the expected port. Use 'netstat -an | findstr :443' (Windows) or 'ss -tuln | grep 443' (Linux) to check. Restart the gRPC server service if needed.
  2. 85% success Check firewall rules. For Windows, run 'netsh advfirewall firewall add rule name="gRPC" dir=in action=allow protocol=TCP localport=443'. For Linux, use 'ufw allow 443/tcp' or adjust iptables. 
    Check firewall rules. For Windows, run 'netsh advfirewall firewall add rule name="gRPC" dir=in action=allow protocol=TCP localport=443'. For Linux, use 'ufw allow 443/tcp' or adjust iptables.
  3. 80% success Ensure the client endpoint URL matches the server's listening address. For example, if the server uses 'https://localhost:5001', the client should set 'new GrpcChannel.ForAddress("https://localhost:5001")'. Use DNS resolution with 'nslookup server.example.com' to verify IP. 
    Ensure the client endpoint URL matches the server's listening address. For example, if the server uses 'https://localhost:5001', the client should set 'new GrpcChannel.ForAddress("https://localhost:5001")'. Use DNS resolution with 'nslookup server.example.com' to verify IP.

中文步骤

  1. Verify the server is running and listening on the expected port. Use 'netstat -an | findstr :443' (Windows) or 'ss -tuln | grep 443' (Linux) to check. Restart the gRPC server service if needed.
  2. Check firewall rules. For Windows, run 'netsh advfirewall firewall add rule name="gRPC" dir=in action=allow protocol=TCP localport=443'. For Linux, use 'ufw allow 443/tcp' or adjust iptables.
  3. Ensure the client endpoint URL matches the server's listening address. For example, if the server uses 'https://localhost:5001', the client should set 'new GrpcChannel.ForAddress("https://localhost:5001")'. Use DNS resolution with 'nslookup server.example.com' to verify IP.

Dead Ends

Common approaches that don't work:

  1. Increasing the deadline or timeout in the gRPC call 95% fail

    The server is not responding at all; a longer timeout only delays the failure but does not establish a connection.

  2. Disabling SSL/TLS on the client side 80% fail

    If the server requires HTTPS, disabling TLS will cause a different error (e.g., protocol mismatch), not fix the connection refusal.

  3. Changing the port number arbitrarily 90% fail

    Unless the correct port is used, the connection will still be refused; this is a guess rather than a fix.