开发与生产环境均出现Client has disconnected错误求助

我们的应用采用Angular前端、.NET Core 6.0后端，在开发、生产及调试环境均出现Client has disconnected错误，排查多日无果，调整服务器配置无效，报错堆栈信息如下：

Microsoft.AspNetCore.Connections.ConnectionResetException
HResult=0x80131620
Message=The client has disconnected
Source=Microsoft.AspNetCore.Server.IIS
StackTrace:
at Microsoft.AspNetCore.Server.IIS.Core.IO.AsyncIOOperation.GetResult(Int16 token)
at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContext.<ReadBody>d__385.MoveNext()
at System.IO.Pipelines.Pipe.GetReadResult(ReadResult& result)
at System.IO.Pipelines.Pipe.ReadAsync(CancellationToken token)
at System.IO.Pipelines.Pipe.DefaultPipeReader.ReadAsync(CancellationToken cancellationToken)
at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContext.<ReadAsync>d__381.MoveNext()
at System.Runtime.CompilerServices.ValueTaskAwaiter1.GetResult()
at Microsoft.AspNetCore.Server.IIS.Core.HttpRequestStream.<ReadAsyncInternal>d__10.MoveNext()
at System.Runtime.CompilerServices.ValueTaskAwaiter1.GetResult()
at Microsoft.AspNetCore.WebUtilities.FileBufferingReadStream.<ReadAsync>d__40.MoveNext()
at System.Runtime.CompilerServices.ValueTaskAwaiter`1.GetResult()
at Microsoft.AspNetCore.WebUtilities.StreamHelperExtensions.<DrainAsync>d__3.MoveNext()
at Microsoft.AspNetCore.Mvc.Formatters.NewtonsoftJsonInputFormatter.<ReadRequestBodyAsync>d__12.MoveNext()
at Microsoft.AspNetCore.Mvc.ModelBinding.Binders.BodyModelBinder.<BindModelAsync>d__11.MoveNext()
at Microsoft.AspNetCore.Mvc.ModelBinding.ParameterBinder.<BindModelAsync>d__8.MoveNext()
at Microsoft.AspNetCore.Mvc.Controllers.ControllerBinderDelegateProvider.<>c__DisplayClass0_0.<<CreateBinderDelegate>g__Bind|0>d.MoveNext()
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<<InvokeInnerFilterAsync>g__Awaited|13_0>d.MoveNext()
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<<InvokeFilterPipelineAsync>g__Awaited|20_0>d.MoveNext()
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<<InvokeAsync>g__Logged|17_1>d.MoveNext()
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<<InvokeAsync>g__Logged|17_1>d.MoveNext()
at Microsoft.AspNetCore.Routing.EndpointMiddleware.<<Invoke>g__AwaitRequestTask|6_0>d.MoveNext()
at Microsoft.AspNetCore.Authorization.Policy.AuthorizationMiddlewareResultHandler.<HandleAsync>d__0.MoveNext()
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.<Invoke>d__6.MoveNext()
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.<Invoke>d__6.MoveNext()
at Camms.Risk.Webapi.Middlewares.ExceptionMiddleware.<InvokeAsync>d__4.MoveNext() in C:\Projects\Git\Camms.Risk\Camms.Risk\Camms.Risk.Webapi\Middlewares\ExceptionMiddleware.cs:line 34

Inner Exception 1:
COMException: An operation was attempted on a nonexistent network connection. (0x800704CD)

排查解决思路 #

• 前端请求生命周期检查

  • 确认Angular端是否存在请求发送后主动中断的情况：比如路由跳转、组件销毁时未取消HTTP请求，导致后端还在处理时前端断开连接。用RxJS的takeUntil操作符绑定组件生命周期，确保组件销毁时自动取消未完成的请求。
  • 检查大文件传输场景：如果有上传/大请求体操作，前端可能因超时或网络波动主动断开。调整Angular的HTTP请求超时配置，后端同步修改Program.cs中Kestrel的最大请求体限制和超时时间：

    builder.WebHost.ConfigureKestrel(options =>
    {
        options.Limits.MaxRequestBodySize = 104857600; // 100MB
        options.Limits.KeepAliveTimeout = TimeSpan.FromMinutes(5);
    });
    

• 后端异常处理与配置优化

  • 检查自定义异常中间件：从堆栈看错误触发在ExceptionMiddleware第34行，在中间件中捕获ConnectionResetException，判断为客户端主动断开后直接终止处理，避免错误日志泛滥：

    public async Task InvokeAsync(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (ConnectionResetException)
        {
            // 客户端已断开，无需处理，直接返回
            context.Response.StatusCode = StatusCodes.Status499ClientClosedRequest;
        }
        catch (Exception ex)
        {
            // 其他异常处理逻辑
        }
    }
    

  • 调整IIS应用程序池配置：延长Idle Time-out时间，增大Ping Maximum Response Time，避免应用池提前回收导致连接断开。

• 网络层排查

  • 检查防火墙/代理服务器：确认是否存在防火墙、反向代理（如Nginx、IIS ARR）在请求未完成时主动断开连接，调整代理的超时时间和连接保持设置。
  • 查看系统日志：Windows服务器查看事件查看器的系统日志，排查是否有TCP连接异常断开的系统级错误；开发环境用Wireshark抓包，分析网络连接状态。

• .NET Core版本与配置调整

  • 禁用不必要的请求体缓冲：如果业务不需要缓冲请求体，在控制器方法添加[DisableRequestSizeLimit]特性，或全局配置：

    builder.Services.Configure<FormOptions>(options =>
    {
        options.BufferBody = false;
    });
    

  • 升级.NET Core补丁：当前使用的.NET Core 6.0如果是旧版本，升级到最新的补丁版本，修复官方已知的连接处理Bug。

内容的提问来源于stack exchange，提问作者Hashan S.