Скачать или смотреть Resolving Grpc.Core.RpcException: Troubleshooting gRPC Connection Issues

Learn how to diagnose and fix the `Grpc.Core.RpcException` with a status code of "Unavailable" in your gRPC applications. We break down the problem and solution step-by-step.
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This video is based on the question https://stackoverflow.com/q/70152113/ asked by the user 'Борис Яницкий' ( https://stackoverflow.com/u/17477817/ ) and on the answer https://stackoverflow.com/a/70153640/ provided by the user 'Борис Яницкий' ( https://stackoverflow.com/u/17477817/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding gRPC Connection Issues

If you're working with gRPC services and encounter the frustrating Grpc.Core.RpcException with a status code of "Unavailable", you're not alone. This error often signifies that the gRPC call to your server could not be completed due to connection-related issues. The detailed error message typically includes hints about the exact problem:

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In this guide, we will delve into the potential causes of this error and guide you through the process of resolving it effectively.

The Problem Breakdown

The core of the issue stems from several factors related to networking and how your gRPC server is set up. Below are some common reasons that can lead to an RpcException stating "Unavailable":

Server not running: The gRPC server may not be running at the specified address and port.

Incorrect URL: The client may be trying to access the wrong URL.

Firewall issues: A firewall may be blocking the connection to the required port.

Listening Port Configuration: The server may not be explicitly configured to listen on the correct port.

Investigating the Solution

In the particular case presented, the solution required an adjustment to the server's listening port. Here’s how to fix it step-by-step:

Step 1: Check Service Code

First, let’s review the server-side code. Here's the critical part of the Worker.cs file that needs attention:

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It is essential to explicitly specify the port on which the server should listen for incoming gRPC calls.

Step 2: Explicitly Set Listening Port

To resolve the issue, modify the listening settings to specify a clear port number, for example, 5001:

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This change ensures that the server listens specifically on https://localhost:5001, which matches the client's connection address.

Step 3: Verify Client Code

Next, make sure your client code points to the correct address. Here's the relevant snippet from Program.cs of your gRPC client:

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Ensure that this matches the port specified in your server code.

Step 4: Firewall and Network Settings

If you've confirmed that both your server and client code are correctly set up, the next step is to check network conditions:

Ensure that port 5001 is not being blocked by your firewall or other security settings.

If you're working within a virtual machine or Docker container, additional network configuration may be required.

Conclusion

By explicitly setting your gRPC server to listen on port 5001 and ensuring that your client connects to the same port, you can eliminate the Grpc.Core.RpcException with a status of "Unavailable." Connection issues can be tricky to navigate, but with careful attention to details such as listening ports and network settings, you can get your gRPC services up and running smoothly.

If you’ve implemented these changes and still face issues, consider reaching out to your network administrator or check the detailed server logs for additional clues.

Happy coding!