ASP.NET MVC POST incorrectly returning HTTP 302

Question

I've looked all over and can't find an answer to this. I have a simple test controller in ASP.NET MVC4 set up as follows:

public class TestController {
    [HttpGet]
    public ActionResult Index() {
        MyModel model = new MyModel();
        model.Debug += "GET Method";
        return View(model);
    }

    [HttpPost]
    public ActionResult Post(MyModel model) {
        model.Debug += "POST Method";
        return View("Index", model);
    }
}

The Index view just has a form and a button that POSTs to /Test/Post which should just return HTTP 200 with the Index view. That works as expected on my laptop and on my server. But on the hosting provider I get the following when I perform the POST:

POST /Test/Post returns HTTP 302 Redirect to /Test/Post (What the heck?)
GET /Test/Post returns HTTP 404

How could this possibly happen? Any ideas for troubleshooting this problem?

The only difference that I know of between the environments is that I have .NET 4.5 installed and they have .NET 4.0 installed (and won't install 4.5 for some reason.) The projects target .NET 4 though, so don't think it would matter? Originally I had them targeting 4.5, but changed it after I learned that it isn't installed on the server.

Searching for ASP.NET POSTs returning 302 brings up a lot of questions about redirecting due to logins. But this controller isn't under any sort of restricted folder or [Authorize] attribute.

---

Update - web.config's

I've tried it with and without <authorization>, same results either way. Here is the system.web, in case this will help:

  <system.web>
    <customErrors mode="Off"/>
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Web.Helpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Web.WebPages, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
      </assemblies>
    </compilation>
    <authentication mode="Forms">
      <forms loginUrl="~/Account/LogOn" timeout="30"/>
    </authentication>
    <membership>
      <providers>
        <clear/>
        <add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="Database" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/"/>
      </providers>
    </membership>
    <pages controlRenderingCompatibilityVersion="4.0">
      <namespaces>
        <add namespace="System.Web.Helpers"/>
        <add namespace="System.Web.Mvc"/>
        <add namespace="System.Web.Mvc.Ajax"/>
        <add namespace="System.Web.Mvc.Html"/>
        <add namespace="System.Web.Routing"/>
        <add namespace="System.Web.WebPages"/>
        <add namespace="Microsoft.Web.Mvc"/>
        <add namespace="Tenido.Domain"/>
        <add namespace="Tenido.Web.Mvc.Controllers"/>
      </namespaces>
    </pages>
    <httpModules>
      <add name="ImageResizingModule" type="ImageResizer.InterceptModule"/>
    </httpModules>
  </system.web>

Answer 1

For me, we had error redirect configured for custom errors via web.config

<system.web> 
...  

 <customErrors mode="On" defaultRedirect="~/error/errorpage">
...

</customErrors>

It was doing a 302 after an internal error. Setting customErrors mode="Off" bubbled the error up all the way to the browser.

Answer 2

Use AllowAnonymous attribute in your controller Method

[AllowAnonymous]
[HttpGet]
public ActionResult Index() {
    MyModel model = new MyModel();
    model.Debug += "GET Method";
    return View(model);
}

Hope it helps