System.Net.Http.HttpRequestException – Connection reset by peer

The System.Net.Http.HttpRequestException with the message “Connection reset by peer” is an exception thrown when an HTTP request fails due to the remote server abruptly closing the connection. This typically occurs due to network issues, server-side problems, or misconfigured client or server settings.

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Key Points

• This exception is specific to the System.Net.Http namespace, commonly used with HttpClient.
• It indicates that the remote server (peer) closed the connection unexpectedly.
• Common causes include network instability, server overload, or misconfigured timeouts.

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Common Causes

1. Network Issues:

• Unstable or unreliable network connections.
• Firewall or proxy interference.

1. Server-Side Problems:

• The remote server is overloaded or crashed.
• The server closed the connection due to a timeout or misconfiguration.

1. Client-Side Issues:

• The client took too long to send or receive data, causing the server to close the connection.
• Misconfigured HttpClient settings (e.g., timeouts).

1. Protocol Mismatch:

• The client and server are using incompatible protocols or versions (e.g., HTTP/1.1 vs. HTTP/2).

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How to Fix

Client-Side Fixes

1. Retry the Request:

• Implement a retry mechanism to handle transient network errors.

   int retryCount = 3;
   while (retryCount > 0)
   {
       try
       {
           HttpResponseMessage response = await httpClient.GetAsync("https://example.com");
           response.EnsureSuccessStatusCode();
           break;
       }
       catch (HttpRequestException ex) when (ex.Message.Contains("Connection reset by peer"))
       {
           retryCount--;
           if (retryCount == 0) throw;
           await Task.Delay(1000); // Wait before retrying
       }
   }

2. Increase Timeout:

• Increase the HttpClient timeout to allow more time for the request to complete.

   httpClient.Timeout = TimeSpan.FromSeconds(30); // Set timeout to 30 seconds

3. Check Network Connectivity:

• Ensure the client has a stable network connection.

3. Use a Reliable HTTP Client:

• Use HttpClientFactory to manage HttpClient instances efficiently and avoid socket exhaustion.

   services.AddHttpClient();

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Server-Side Fixes

1. Increase Server Timeout:

• Configure the server to allow longer connection durations.
• For example, in ASP.NET Core:

   services.Configure<KestrelServerOptions>(options =>
   {
       options.Limits.KeepAliveTimeout = TimeSpan.FromMinutes(5);
   });

2. Handle Server Load:

• Scale the server to handle increased traffic or optimize resource usage.

2. Fix Server Crashes:

• Investigate and resolve issues causing the server to crash or close connections abruptly.

2. Log Errors:

• Log server-side errors to identify and address the root cause.

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Example Scenario

Client Request

using (HttpClient httpClient = new HttpClient())
{
    httpClient.Timeout = TimeSpan.FromSeconds(10);
    try
    {
        HttpResponseMessage response = await httpClient.GetAsync("https://example.com");
        response.EnsureSuccessStatusCode();
    }
    catch (HttpRequestException ex) when (ex.Message.Contains("Connection reset by peer"))
    {
        Console.WriteLine("Connection reset by peer. Please check your network or retry.");
    }
}

Server Logs

[Error] Connection reset by peer. Remote endpoint closed the connection unexpectedly.

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Debugging Tips

1. Check Network Connectivity:

• Use tools like ping or traceroute to diagnose network issues.

1. Inspect Server Logs:

• Review server logs to identify why the connection was reset.

1. Use Tools:

• Use tools like Wireshark or Fiddler to analyze network traffic and identify connection issues.

1. Test with a Different Client:

• Use a different client (e.g., Postman or cURL) to verify if the issue is client-specific.

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