How to Fix Proxy Error in .NET

If you've run into a proxy error in your .NET project, you're not alone. This is one of the most common issues developers face, and fortunately the fix is usually straightforward once you understand the root cause.

Why It Happens

Proxy errors in .NET arise when a request can't reach its destination through an intermediary server. Typical causes include:

• Misconfigured proxy URL, port, or protocol
• The proxy server is down, overloaded, or unreachable
• Timeout settings are too aggressive for the proxy's latency
• SSL/TLS certificate issues when proxying HTTPS traffic
• DNS resolution failures within the proxy network

Fixing the Issue

var handler = new HttpClientHandler
{
    Proxy = new WebProxy("http://proxy.internal:8080"),
    UseProxy = true,
    ServerCertificateCustomValidationCallback =
        HttpClientHandler.DangerousAcceptAnyServerCertificateValidator
        // Only for development! Remove in production.
};
var client = new HttpClient(handler)
{
    Timeout = TimeSpan.FromSeconds(10)
};
try
{
    var response = await client.GetAsync("https://api.example.com/data");
    response.EnsureSuccessStatusCode();
    var data = await response.Content.ReadAsStringAsync();
}
catch (HttpRequestException ex)
{
    logger.LogError("Proxy error: {Message}", ex.Message);
}

Configure HttpClientHandler with proxy settings. Never use DangerousAcceptAnyServerCertificateValidator in production.

Debugging Steps

1. Verify the proxy server is reachable: curl -x proxy:port https://target
2. Check environment variables: HTTP_PROXY, HTTPS_PROXY, NO_PROXY
3. Ensure DNS resolution works within your network environment
4. Review firewall rules between your app and the proxy server
5. Test with increased timeouts to rule out latency issues

Monitor proxy failures across all your services with [Bugsly](https://bugsly.dev) to spot network infrastructure issues before they cascade into outages.