Response.End not working inside Razor Class Library

[gumbarros]

Describe the bug

Trying to use Response.End from a Controller inside a Razor Class Library causes the exception bellow.

To Reproduce

        app.MapControllerRoute(
                name: "DataDictionary",
                pattern: "{culture}/{area:exists}/{controller=Element}/{action=Index}/{dictionaryName?}/")
            .PreBufferRequestStream().BufferResponseStream();
        app.MapControllerRoute(
                name: "MasterData",
                pattern: "{culture}/{area:exists}/{controller=Log}/{action=Index}/{dictionaryName?}/")
            .PreBufferRequestStream().BufferResponseStream();

Exceptions (if any)

Microsoft.AspNetCore.Server.Kestrel[13]
Connection id "0HMJ5RQTKTINH", Request id "0HMJ5RQTKTINH:00000175": An unhandled exception was thrown by the application.
System.InvalidOperationException: Headers are read-only, response has already started.
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpHeaders.ThrowHeadersReadOnlyException()
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpResponseHeaders.Microsoft.AspNetCore.Http.IHeaderDictionary.set_ContentType(StringValues value)
at Microsoft.AspNetCore.Http.DefaultHttpResponse.set_ContentType(String value)
at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable1 statusCode) at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ActionContext actionContext, IView view, ViewDataDictionary viewData, ITempDataDictionary tempData, String contentType, Nullable1 statusCode)
at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewResultExecutor.ExecuteAsync(ActionContext context, ViewResult result)
at Microsoft.AspNetCore.Mvc.ViewResult.ExecuteResultAsync(ActionContext context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|25_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.InvokeFilterPipelineAsync()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Localization.RequestLocalizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.SystemWebAdapters.BufferResponseStreamMiddleware.BufferResponseStreamAsync(HttpContext context, IHttpResponseBodyFeature feature, IBufferResponseStreamMetadata metadata)
at Microsoft.AspNetCore.SystemWebAdapters.PreBufferRequestStreamMiddleware.PreBufferAsync(HttpContext context, IPreBufferRequestStreamMetadata metadata)
at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.HandleException(HttpContext context, ExceptionDispatchInfo edi)
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

*ASP.NET Core Application*:
- Targeted .NET version:6.0
- .NET SDK version:6.0

[adityamandaleeka]

Can you please share your controller code as well?

[gumbarros]

@adityamandaleeka The controller code have a huge dependency tree, maybe useless to this review, soon JJMasterData will be open-source. Tried adding the [SingleThreadedRequest] atribute but it don't exists on the public API.

Controller from the RCL

using JJMasterData.Core.WebComponents;
using JJMasterData.Web.Controllers;
using JJMasterData.Web.Models;
using Microsoft.AspNetCore.Mvc;

namespace JJMasterData.Web.Areas.MasterData.Controllers;

[Area("MasterData")]
public class FormController : JJMasterDataController
{
    public IActionResult Render(string dictionaryName)
    {   
        var form = new JJFormView(dictionaryName);
        return View(form);
    }
}

View from the RCL

@using JJMasterData.Web.Extensions
@model JJGridView

@using (Html.BeginForm())
{
    @Model.GetHtml().ToHtmlString()
}

Response.End being used in a deep level on JJMasterData.Core

    /// <summary>
    /// Ends the HttpResponse and sends the data to the client.
    /// </summary>
    /// <param name="data">Data to the client. Can be a HTML or JSON .</param>
    /// <param name="contentType">Optional. Usually application/json</param>
    public void SendResponse(string data, string contentType = null)
    {
        if (this.HasStarted) return;

        SystemWebCurrent.Response.Clear();
        
        if (contentType != null)
        {
            SystemWebCurrent.Response.ContentType = contentType;
        }

        WriteResponse(data);
        SystemWebCurrent.Response.End();
    }
    
        /// <summary>
    /// Writes content to the response.
    /// </summary>
    /// <param name="data">Data to the client. Can be a HTML or JSON .</param>
    public void WriteResponse(string data)
    {
#if NETFRAMEWORK
        SystemWebCurrent.Response.Write(data);
#else
        AspNetCoreCurrent.Response.WriteAsync(data).GetAwaiter().GetResult();
#endif
    }

[twsouthwick]

How was this code used in .NET Framework? Calling End() seems like it would fail in a view there as well....

[gumbarros]

It's insane, but this exact Controller works on .NET Framework too, on both WebForms and MVC. The front-end does alot of JS calls to the back-end and the method GetHtml get re-called.

[gumbarros]

I also implemented on my application the source code of SingleThreadedRequestAttribute and a SingleThreadedMiddleware but no success.

[twsouthwick]

@gumbarros I'd like to try to repro this, but I can't see how the sample you shared would actually tie together. How does the controller end up at the SendResponse() method?

[gumbarros]

Good morning, solved using SystemWebCurrent.Response.ClearContent() instead of SystemWebCurrent.Response.Clear().

Makes sense reading the exceptions logs, .NET Core don't support clearing the Headers while the response already started.

[twsouthwick]

@gumbarros Since this worked on framework, I'd still love to see a full repro of what you're doing in case there's something we can do here.

[gumbarros]

@twsouthwick We're adding support to .NET Core in our CRUD generator based on database metadata. Also in this migration, we're going to open-source it to the community. We're writing some tests and creating documentation before releasing for the general public, in a few weeks is the prevision to release it. Copying and pasting code will not work, the codebase is very very huge. If you really want, I can send a copy of the project in your email without the Git (we have some private information in some commits before creating a new public repo).

[gumbarros]

On Preview 3 getting the following error:

warn: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[2]
      The response has already started, the error page middleware will not be executed.
fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HMJF6U3HGAIO", Request id "0HMJF6U3HGAIO:0000005B": An unhandled exception was thrown by the application.
      System.InvalidOperationException: Headers are read-only, response has already started.
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpHeaders.ThrowHeadersReadOnlyException()
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpResponseHeaders.Microsoft.AspNetCore.Http.IHeaderDictionary.set_ContentType(StringValues value)
         at Microsoft.AspNetCore.Http.DefaultHttpResponse.set_ContentType(String value)
         at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable`1 statusCode)
         at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ActionContext actionContext, IView view, ViewDataDictionary viewData, ITempDataDictionary tempData, String contentType, Nullable`1 statusCode)
         at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewResultExecutor.ExecuteAsync(ActionContext context, ViewResult result)
         at Microsoft.AspNetCore.Mvc.ViewResult.ExecuteResultAsync(ActionContext context)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|25_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.InvokeFilterPipelineAsync()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
         at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
         at Microsoft.AspNetCore.SystemWebAdapters.BufferResponseStreamMiddleware.BufferResponseStreamAsync(HttpContext context, IHttpResponseBodyFeature feature, BufferResponseStreamAttribute metadata)
         at Microsoft.AspNetCore.SystemWebAdapters.BufferResponseStreamMiddleware.BufferResponseStreamAsync(HttpContext context, IHttpResponseBodyFeature feature, BufferResponseStreamAttribute metadata)
         at Microsoft.AspNetCore.SystemWebAdapters.PreBufferRequestStreamMiddleware.PreBufferAsync(HttpContext context, PreBufferRequestStreamAttribute metadata)
         at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Localization.RequestLocalizationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
         at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.HandleException(HttpContext context, ExceptionDispatchInfo edi)
         at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserRefreshMiddleware.InvokeAsync(HttpContext context)
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

Happens when Response.End already happened and the code reaches return View()

[gumbarros]

Another update:

Calling Response.End inside the view don't cause errors, calling from the Controller causes.