406 Not Accepted when returning ObjectResult with content type 'application/json; charset=utf-8'

[angularsen]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Returning ObjectResult from API action with ContentTypes = ["application/json; charset=utf-8"] results in 406 Not Accepted.

It fails to match with Microsoft.AspNetCore.Mvc.Formatters.NewtonsoftJsonOutputFormatter due to the ; charset=utf-8 suffix.

By changing it to ContentTypes = ["application/json"], it returns 200 OK with JSON response as expected.

Why this happens

NewtonsoftJsonOutputFormatter.CanWriteResult returns false, because MediaTypeHeaderValue.IsSubsetOf() and MediaTypeHeaderValue.MatchesParameters() fail to recognize that Accept: application/json is compatible with Content-Type: application/json; charset=utf-8

Not sure if this is a bug or by design, but I expected it to be able to match regardless of charset - or at least if the charset matched what it would output itself.

Related issue on using IdempotentAPI to cache responses with this content type: ikyriak/IdempotentAPI#78

Sample code

[ApiController]
[Route("[controller]")]
public class FooController : ControllerBase
{
    [HttpGet("fail")]
    public IActionResult Fail()
    {
        return new ObjectResult(new
        {
            Message = """
                      This will fail with 406 Not Accepted due to unsupported response content type 'application/json; charset=utf-8':

                      Error message: 
                      No output formatter was found for content types 'application/json; charset=utf-8, application/json; charset=utf-8' to write the response.
                      """
        })
        {
            ContentTypes = ["application/json; charset=utf-8"],
            StatusCode = 200
        };
    }

    [HttpGet("pass")]
    public IActionResult Pass()
    {
        return new ObjectResult(new
        {
            Message = """
                      This will succeed due to supported response content type 'application/json'.
                      """
        })
        {
            ContentTypes = ["application/json"],
            StatusCode = 200
        };
    }
}

Log output

Key log entries:

Microsoft.AspNetCore.Mvc.Infrastructure.DefaultOutputFormatterSelector[9]
Attempting to select the first output formatter in the output formatters list which supports a content type from the explicitly specified content types 'application/json; charset=utf-8'.

Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor[2]
      No output formatter was found for content types 'application/json; charset=utf-8, application/json; charset=utf-8' to write the response.

Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished HTTP/1.1 GET http://localhost:5176/foo/fail - 406 0 - 154.7296ms

Full log for GET http://localhost:5176/foo/fail

info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/1.1 GET http://localhost:5176/foo/fail - - -
dbug: Microsoft.AspNetCore.HostFiltering.HostFilteringMiddleware[0]
      Wildcard detected, all requests with hosts will be allowed.
trce: Microsoft.AspNetCore.HostFiltering.HostFilteringMiddleware[2]
      All hosts are allowed.
dbug: Microsoft.AspNetCore.Routing.Matching.DfaMatcher[1001]
      1 candidate(s) found for the request path '/foo/fail'
dbug: Microsoft.AspNetCore.Routing.Matching.DfaMatcher[1005]
      Endpoint 'WebApplication2.Controllers.FooController.Fail (WebApplication2)' with route pattern 'Foo/fail' is valid for the request path '/foo/fail'
dbug: Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware[1]
      Request matched endpoint 'WebApplication2.Controllers.FooController.Fail (WebApplication2)'
trce: Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware[8]
      The endpoint does not specify the IRequestSizeLimitMetadata.
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
      Executing endpoint 'WebApplication2.Controllers.FooController.Fail (WebApplication2)'
info: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[102]
      Route matched with {action = "Fail", controller = "Foo"}. Executing controller action with signature Microsoft.AspNetCore.Mvc.IActionResult Fail() on controller WebApplication2.Controllers.FooController (WebApplication2).
dbug: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[1]
      Execution plan of authorization filters (in the following order): None
dbug: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[1]
      Execution plan of resource filters (in the following order): None
dbug: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[1]
      Execution plan of action filters (in the following order): Microsoft.AspNetCore.Mvc.ModelBinding.UnsupportedContentTypeFilter (Order: -3000), Microsoft.AspNetCore.Mvc.Infrastructure.ModelStateInvalidFilter (Order: -2000)
dbug: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[1]
      Execution plan of exception filters (in the following order): None
dbug: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[1]
      Execution plan of result filters (in the following order): Microsoft.AspNetCore.Mvc.Infrastructure.ClientErrorResultFilter (Order: -2000)
dbug: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[1]
      Executing controller factory for controller WebApplication2.Controllers.FooController (WebApplication2)
dbug: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[2]
      Executed controller factory for controller WebApplication2.Controllers.FooController (WebApplication2)
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[52]
      Action Filter: Before executing OnActionExecuting on filter Microsoft.AspNetCore.Mvc.ModelBinding.UnsupportedContentTypeFilter.
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[53]
      Action Filter: After executing OnActionExecuting on filter Microsoft.AspNetCore.Mvc.ModelBinding.UnsupportedContentTypeFilter.
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[52]
      Action Filter: Before executing OnActionExecuting on filter Microsoft.AspNetCore.Mvc.Infrastructure.ModelStateInvalidFilter.
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[53]
      Action Filter: After executing OnActionExecuting on filter Microsoft.AspNetCore.Mvc.Infrastructure.ModelStateInvalidFilter.
info: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[101]
      Executing action method WebApplication2.Controllers.FooController.Fail (WebApplication2) - Validation state: Valid
info: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[103]
      Executed action method WebApplication2.Controllers.FooController.Fail (WebApplication2), returned result Microsoft.AspNetCore.Mvc.ObjectResult in 0.4942ms.
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[52]
      Action Filter: Before executing OnActionExecuted on filter Microsoft.AspNetCore.Mvc.Infrastructure.ModelStateInvalidFilter.
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[53]
      Action Filter: After executing OnActionExecuted on filter Microsoft.AspNetCore.Mvc.Infrastructure.ModelStateInvalidFilter.
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[52]
      List of registered output formatters, in the following order: Microsoft.AspNetCore.Mvc.Formatters.HttpNoContentOutputFormatter, Microsoft.AspNetCore.Mvc.Formatters.StringOutputFormatter, Microsoft.AspNetCore.Mvc.Formatters.StreamOutputFormatter, Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter
dbug: Microsoft.AspNetCore.Mvc.Infrastructure.DefaultOutputFormatterSelector[4]
      No information found on request to perform content negotiation.
dbug: Microsoft.AspNetCore.Mvc.Infrastructure.DefaultOutputFormatterSelector[9]
      Attempting to select the first output formatter in the output formatters list which supports a content type from the explicitly specified content types 'application/json; charset=utf-8'.
warn: Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor[2]
      No output formatter was found for content types 'application/json; charset=utf-8, application/json; charset=utf-8' to write the response.
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[6]
      After executing action result Microsoft.AspNetCore.Mvc.ObjectResult.
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[52]
      Result Filter: Before executing OnResultExecuted on filter Microsoft.AspNetCore.Mvc.Infrastructure.ClientErrorResultFilter.
trce: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[53]
      Result Filter: After executing OnResultExecuted on filter Microsoft.AspNetCore.Mvc.Infrastructure.ClientErrorResultFilter.
info: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[105]
      Executed action WebApplication2.Controllers.FooController.Fail (WebApplication2) in 55.8371ms
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
      Executed endpoint 'WebApplication2.Controllers.FooController.Fail (WebApplication2)'
dbug: Microsoft.AspNetCore.Server.Kestrel.Connections[9]
      Connection id "0HN4HQQ1PUQ06" completed keep alive response.
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished HTTP/1.1 GET http://localhost:5176/foo/fail - 406 0 - 154.7296ms

Expected Behavior

Expected GET http://localhost:5176/foo/fail to return 200 OK, with JSON response.
It returns 406 Not Accepted with no body.

GET http://localhost:5176/foo/pass does return 200 OK with JSON response.

Steps To Reproduce

repro-406-notaccepted-when-json-has-charset.zip

1. Extract zip
2. dotnet run
3. Call GET http://localhost:5176/foo/fail, it returns 406 Not Accepted, but expected 200 OK with JSON body
4. Call GET http://localhost:5176/foo/pass, it returns 200 OK as expected

It also does not help to specify any of these Accept headers in request:

• Accept: application/json; charset=utf-8
• Accept: application/json
• Accept: application/*
• Accept: */*

Exceptions (if any)

No response

.NET Version

8.0.301

Anything else?

Related issues

406 Not Accepted on cached response with Content-Type: application/json; charset=utf-8 · Issue #78 · ikyriak/IdempotentAPI

Versions

ASP.NET Core 8.0.6

dotnet --info

.NET SDK:
 Version:           8.0.301
 Commit:            1a0e9c0300
 Workload version:  8.0.300-manifests.011fccd5
 MSBuild version:   17.10.4+10fbfbf2e

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.22631
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\8.0.301\

.NET workloads installed:
 [android]
   Installation Source: SDK 8.0.300, VS 17.9.34902.65
   Manifest Version:    34.0.95/8.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.android\34.0.95\WorkloadManifest.json
   Install Type:              Msi

 [ios]
   Installation Source: SDK 8.0.300, VS 17.9.34902.65
   Manifest Version:    17.2.8053/8.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.ios\17.2.8053\WorkloadManifest.json
   Install Type:              Msi

 [maccatalyst]
   Installation Source: SDK 8.0.300, VS 17.9.34902.65
   Manifest Version:    17.2.8053/8.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.maccatalyst\17.2.8053\WorkloadManifest.json
   Install Type:              Msi

 [maui-windows]
   Installation Source: SDK 8.0.300, VS 17.9.34902.65
   Manifest Version:    8.0.21/8.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.maui\8.0.21\WorkloadManifest.json
   Install Type:              Msi

 [wasi-experimental]
   Installation Source: SDK 8.0.300
   Manifest Version:    8.0.6/8.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.workload.mono.toolchain.current\8.0.6\WorkloadManifest.json
   Install Type:              Msi


Host:
  Version:      8.0.6
  Architecture: x64
  Commit:       3b8b000a0e

.NET SDKs installed:
  5.0.408 [C:\Program Files\dotnet\sdk]
  6.0.321 [C:\Program Files\dotnet\sdk]
  6.0.423 [C:\Program Files\dotnet\sdk]
  7.0.120 [C:\Program Files\dotnet\sdk]
  7.0.317 [C:\Program Files\dotnet\sdk]
  8.0.106 [C:\Program Files\dotnet\sdk]
  8.0.205 [C:\Program Files\dotnet\sdk]
  8.0.301 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.26 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.31 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.19 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.26 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.30 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.31 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.19 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.26 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.30 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.31 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 7.0.19 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
  x86   [C:\Program Files (x86)\dotnet]
    registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

[vanbukin]

The issue stems from MediaTypeHeaderValue.IsSubsetOf treating parameters (like charset) as part of the comparison, even though application/json; charset=utf-8 is semantically equivalent to application/json for the purpose of JSON response formatting.