Error in MVC redirect: Server cannot append header after HTTP headers have been sent

Question

I want to do a simple redirect when a user first loads the website. For that, I just access the RouteData on BeginExecuteCore() method of BaseController and if URL does not have a specific value, then I will redirect to another https route:

  public class BaseController : Controller
  {
        protected override IAsyncResult BeginExecuteCore(AsyncCallback callback, object state)
        {
            // access route data

            if (condition == true)
               Response.Redirect(string.Format("https://{0}/en/en", Request.Url.Authority), true);
            }
        }
  }

Some facts:

I achieve the result I want
I get the Exception "Server cannot append header after HTTP headers have been sent."
I've tried several alternatives: Using other methods to do the redirect like Initialize(RequestContext requestContext) etc
I tried to Use parameter EndResponse=true on Redirect method
I tried to clear the headers before doing the redirect
In all the previous experiments I got the same exception
I'm using MVC 5

My question is: How can I redirect the user to another route in the most efficient way knowing that I need to have access to RouteData and without throwing the annoying exception?

Thank you!

Community · Accepted Answer · 2017-05-23 11:52:32Z

1

Response.Redirect(anyUrl) cause 302 status code And Html.AntiForgeryToken() has conflict with 302 status code normally.

You can put the following code in Application_Start:

AntiForgeryConfig.SuppressXFrameOptionsHeader = true;

Security Warning: SuppressXFrameOptionsHeader =true prevents your site from being loaded into an iframe.

Comments

Jamie · Accepted Answer · 2014-04-25 11:00:55Z

0

I'm not familiair with the method BeginExecuteCore() as i am still working with mvc 3 and 4.

In mvc 4 i would use an action filter to check something before a page loads.

The reason why you are seeing that error is probably because you are to late redirecting the user as the page is already being loaded.

 public class LogActionFilter : ActionFilterAttribute
   {
          public override void OnActionExecuting(ActionExecutingContext filterContext)
          {
                if (condition == true)
               filterContext.Response.Redirect(string.Format("https://{0}/en/en", Request.Url.Authority), true);
          }     
     }

Take a look at: http://www.asp.net/mvc/tutorials/older-versions/controllers-and-routing/understanding-action-filters-cs

answered Apr 25, 2014 at 11:00

Jamie

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2 Comments

sergiommaria Over a year ago

Unfortunately it didn't. I got the same exception. Here's what I did (to be sure I didn't anything that I shouldn't) 1. I adapted your method because there are some change in the way filterContext exposes Request and Response (it worked and I could retrieve the info I needed) 2. Decorated BaseController with with [LogActionFilter]

sergiommaria Over a year ago

3. Also tried to decorate HomeController instead of BaseController without success.. This code is called after the previous code I have so I think the probability of trying to redirect the user when the page is being loading is higher

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