Azure Web App中.NET Core 3.1 MVC请求间歇性失败求助

问题概述 #

在Azure Web App部署的.NET Core 3.1 MVC应用中，处理约1MB大小的请求时出现间歇性失败：前两次请求报错，第三次成功；本地运行无此问题。报错核心信息：

The client has disconnected <--- An operation was attempted on a nonexistent network connection. (0x800704CD)

完整异常栈：

[Error] Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: An unhandled exception has occurred while executing the request.Microsoft.AspNetCore.Connections.ConnectionResetException: The client has disconnected---> System.Runtime.InteropServices.COMException (0x800704CD): An operation was attempted on a nonexistent network connection. (0x800704CD)---> End of inner exception stack trace ---at Microsoft.AspNetCore.Server.IIS.Core.IO.AsyncIOOperation.GetResult(Int16 token)at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContext.ReadBody()at System.IO.Pipelines.PipeCompletion.ThrowLatchedException()at System.IO.Pipelines.Pipe.GetReadResult(ReadResult& result)at System.IO.Pipelines.Pipe.GetReadAsyncResult()at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContext.ReadAsync(Memory`1 memory, CancellationToken cancellationToken)at Microsoft.AspNetCore.Server.IIS.Core.HttpRequestStream.ReadAsyncInternal(Memory`1 buffer, CancellationToken cancellationToken)at System.IO.Pipelines.StreamPipeReader.ReadAsync(CancellationToken cancellationToken)at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ReadFormAsync(CancellationToken cancellationToken)at Microsoft.AspNetCore.Http.Features.FormFeature.InnerReadFormAsync(CancellationToken cancellationToken)
at Microsoft.AspNetCore.Mvc.ModelBinding.FormValueProviderFactory.AddValueProviderAsync(ValueProviderFactoryContext context)at Microsoft.AspNetCore.Mvc.ModelBinding.CompositeValueProvider.CreateAsync(ActionContext actionContext, IList`1 factories)at Microsoft.AspNetCore.Mvc.ModelBinding.CompositeValueProvider.TryCreateAsync(ActionContext actionContext, IList`1 factories)at Microsoft.AspNetCore.Mvc.Controllers.ControllerBinderDelegateProvider.<>c__DisplayClass0_0.<g__Bind|0>d.MoveNext()--- End of stack trace from previous location where exception was thrown ---at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Logged|17_1(ResourceInvoker invoker)at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

环境信息 #

• .NET框架：.NET Core 3.1
• 应用类型：MVC Core App
• Azure Web App配置：.NET 6 LTS
• 其他配置：64位、集成管道、HTTP 1.1、WebSocket关闭、TLS 1.2

已尝试操作 #

• 设置SCM_COMMAND_IDLE_TIMEOUT=600
• 监控显示内存、CPU无峰值，处于正常范围

解决方案 #

1. 调整Azure Web App请求超时与缓冲区配置 #

在Azure门户的Web App配置中，添加以下应用设置：

• ASP.NET_CORE_REQUEST_TIMEOUT: 设置为00:10:00（可根据实际处理耗时调整，10分钟足够覆盖1MB请求的处理）
• WEBSITE_MAX_REQUEST_BUFFER: 设置为10485760（10MB，扩大默认缓冲区限制，适配1MB请求的传输需求）

2. 修正.NET版本不匹配问题 #

当前应用基于.NET Core 3.1开发，但Azure Web App配置为.NET 6 LTS，版本不一致可能引发IIS托管层的兼容性问题：

• 方案一：将Azure Web App的.NET运行时版本切换为.NET Core 3.1
• 方案二：升级应用代码至.NET 6 LTS，适配Azure配置的运行时环境

3. 启用HTTP/2优化连接稳定性 #

当前使用HTTP 1.1，切换到HTTP/2可提升连接可靠性：

• 在Azure Web App配置中，将HTTP version改为2.0

4. 添加异常捕获与重试逻辑 #

在MVC控制器中针对表单读取或模型绑定环节捕获连接重置异常，添加自动重试逻辑：

[HttpPost]
public async Task<IActionResult> YourAction()
{
    int retryCount = 2;
    while(retryCount >= 0)
    {
        try
        {
            var form = await Request.ReadFormAsync();
            // 业务逻辑处理
            return Ok();
        }
        catch(ConnectionResetException)
        {
            retryCount--;
            if(retryCount < 0)
                throw;
            await Task.Delay(100);
        }
    }
    return BadRequest();
}

5. 检查Web App实例状态与资源配置 #

• 若为多实例部署，检查实例健康状态，尝试重启Web App实例
• 确认App Service Plan的资源配额充足，避免因资源节流导致连接中断

内容的提问来源于stack exchange，提问作者Sagar