How to forcefully set IE s Compatibility Mode off from the server-side

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In a domain-controlled environment I m finding that the compatibility mode is triggered on certain clients  winXP Win7  IE8 IE9  even when we are providing a X-UA tags  a  DOCTYPE definition and  IE Edge  response headers  These clients have the  display intranet sites in compatibility view  checkbox ticked  Which is precisely what I m trying to override   The following is the documentation that I ve used to try understand how IE decides to actually trigger the compatibility mode   http   msdn microsoft com en-us library ff406036 28v VS 85 29 aspx  http   blogs msdn com b ie archive 2009 02 16 just-the-facts-recap-of-compatibility-view aspx     Site owners are always in control of their content  Site owners can choose to use the X-UA-Compatible tag to be absolutely declarative about how they   d like their site to display and to map Standards mode pages to IE7 Standards  Use of the X-UA-Compatible tag overrides Compatibility View on the client    Google for  Defining Document Compatibility   sadly the SPAM engine doesn t let me post more than 2 urls   This is an ASP  NET web app and includes the following definitions on the master page    lt  DOCTYPE html PUBLIC  -  W3C  DTD XHTML 1 0 Strict  EN   http   www w3 org TR xhtml1 DTD xhtml1-strict dtd  gt   lt head gt      lt meta http-equiv  X-UA-Compatible  content  IE Edge    gt   lt  head gt    and web config   lt system webServer gt     lt httpProtocol gt       lt customHeaders gt         lt clear   gt         lt add name  X-UA-Compatible  value  IE Edge    gt       lt  customHeaders gt     lt  httpProtocol gt   lt  system webServer gt    I ve used Fiddler to check that the header is indeed being injected correctly   My understanding is that with these settings I should be able override the  Display intranet sites in Compatibility View  browser setting  But depending on the client I ve found that some of them will still trigger compatibility mode  It also seems to be down to the machine level rather a policy group setting  since I obtain different results even when I use with the same set of credentials on different clients   Disabling the Compatibility View Settings checkbox does the trick  But the actual purpose is to make sure that the app is rendered exactly the same way regardless of the client settings   Any thoughts and what I could be possibly missing  Is it possible at all to force IE to always render the pages without triggering Compat mode    thanks a million   Jaume  PS  the site is currently in development and is of course not in Microsoft s compatibility list  but I ve also checked just in case   Google for  Understanding the Compatibility View List   sadly the SPAM engine doesn t let me post more than 2 urls

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Update  More useful information What does  lt meta http-equiv  quot X-UA-Compatible quot  content  quot IE edge quot  gt  do   Maybe this url can help you  Activating Browser Modes with Doctype  Edit  Today we were able to override the compatibility view with    lt meta http-equiv  X-UA-Compatible  content  IE EmulateIE8    gt

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I found problems with the two common ways of doing this   Doing this with custom headers   lt customHeaders gt   in web config allows different deployments of the same application to have this set differently  I see this as one more thing that can go wrong  so I think it s better if the application specifies this in code  Also  IIS6 doesn t support this   Including an HTML  lt meta gt  tag in a Web Forms Master Page or MVC Layout Page seems better than the above  However  if some pages don t inherit from these then the tag needs to be duplicated  so there s a potential maintainability and reliability problem   Network traffic could be reduced by only sending the X-UA-Compatible header to Internet Explorer clients    Well-Structured Applications If your application is structured in a way that causes all pages to ultimately inherit from a single root page  include the  lt meta gt  tag as shown in the other answers  Legacy Applications Otherwise  I think the best way to do this is to automatically add the HTTP header to all HTML responses  One way to do this is using an IHttpModule  public class IeCompatibilityModeDisabler   IHttpModule       public void Init HttpApplication context                context PreSendRequestHeaders     sender  e    gt  DisableCompatibilityModeIfApplicable               private void DisableCompatibilityModeIfApplicable                 if  IsIe  amp  amp  IsPage              DisableCompatibilityMode               private void DisableCompatibilityMode                 var response   Context Response          response AddHeader  quot X-UA-Compatible quot    quot IE edge quot               private bool IsIe   get   return Context Request Browser IsBrowser  quot IE quot             private bool IsPage   get   return Context Handler is Page           private HttpContext Context   get   return HttpContext Current           public void Dispose          IE edge indicates that IE should use its latest rendering engine  rather than compatibility mode  to render the page  It seems that HTTP modules are often registered in the web config file  but this brings us back to the first problem  However  you can register them programmatically in Global asax like this  public class Global   HttpApplication       private static IeCompatibilityModeDisabler module       void Application Start object sender  EventArgs e                module   new IeCompatibilityModeDisabler               public override void Init                 base Init            module Init this            Note that it is important that the module is static and not instantiated in Init so that there is only one instance per application  Of course  in a real-world application an IoC container should probably be managing this  Advantages  Overcomes the problems outlined at the start of this answer   Disadvantages  Website admins don t have control over the header value  This could be a problem if a new version of Internet Explorer comes out and adversely affects the rendering of the website  However  this could be overcome by having the module read the header value from the application s configuration file instead of using a hard-coded value  This may require modification to work with ASP NET MVC  This doesn t work for static HTML pages  The PreSendRequestHeaders event in the above code doesn t seem to fire in IIS6  I haven t figured out how to resolve this bug yet

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For Node Express developers you can use middleware and set this via server   app use function req  res  next      res setHeader  X-UA-Compatible    IE edge      next

User · Answer

Changing my header to the following solve the problem    lt html gt   lt head gt   lt meta http-equiv  X-UA-Compatible  content  IE Edge    gt

[asp.net] How to forcefully set IE's Compatibility Mode off from the server-side?

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