Why does IE9 switch to compatibility mode on my website

Question

I have just installed IE9 beta and on a specific site I created  HTML5  IE9 jumps to compatibility mode unless I manually tell it not to  I have tried removing several parts of the website but no change  Including removing all CSS includes  On some other website of me it goes just fine   Also  don t set it manually because then IE9 remembers the user setting and you can t turn it back to automatic  or at least I haven t found how  not even via private browsing and emptying cache   Anyway  The site where it jumps to compatibility mode  http   alliancesatwar com guide  One where it renders correct  http   geuze name basement   I can t post more than 1 hyperlink   Both use the same doctype and all  Those sites have a lot in common apart from appearance  using the same basic template encoding  meta tags  doctype and the same javascript   It would be great if someone has an answer for me  An HTML5 website that renders in IE7-mode is pretty    lame

User · Answer

To force IE to render in IE9 standards mode you should use

<meta http-equiv="X-UA-Compatible" content="IE=edge">

Some conditions may cause IE9 to jump down into the compatibility modes. By default this can occur on intranet sites.

User · Answer

I put   lt meta http-equiv  X-UA-Compatible  content  IE Edge   gt    first thing after    lt head gt     I read it somewhere  I can t recall   I could not believe it did work

User · Answer

The site at http   www HTML-5 com index html does have the X-UA-Compatible meta tag but still goes into Compatibility View as indicated by the  torn page  icon in the address bar   How do you get the menu option to force IE 9  Final Version 9 0 8112 16421  to render a page in Standards Mode  I tried right clicking that torn page icon as well as the  Alt  key trick to display the additional menu options mentioned by Rene Geuze  but those didn t work

User · Answer

Works in IE9 documentMode for me   Without a X-UA-Compatible header meta to set an explicit documentMode  you ll get a mode based on    whether the user has clicked the    compatibility view    button in that domain before  perhaps also whether this has happened automatically due to some other content on the site causing IE8 9 s renderer to crash and fall back to the old renderer  whether the user has opted to put all sites in compatibility view by default  whether IE thinks the site is on your intranet and so defaults to compatibility view  whether the site in question is in Microsoft s own list of websites that require compatibility view    You can change these settings from    Tools -  Compatibility view settings    from the IE menu  Of course that menu is now sneakily hidden  so you won t see it until you press Alt   As a site author  if you re confident that your site complies to standards  renders well in other browsers  and uses feature-sniffing to decide what browser workarounds to use   I suggest using    lt meta http-equiv  X-UA-Compatible  content  IE Edge   gt    or the HTTP header   X-UA-Compatible  IE Edge   to get the latest renderer whatever IE version is in use

User · Answer

I recently had to resolve this issue and here s what I did    First of all  this solution is around tuning Apache server   Second main think is that there s a bug in the IE9 which means that the meta tag will not work  instead of this solution try this   find open your httpd conf uncomment or add the following line  LoadModule headers module modules mod headers so  add the following lines   lt IfModule headers module gt      Header set X-UA-Compatible  IE EmulateIE8  lt  IfModule gt   save restart your Apache server   browse to your page with IE9  use tools like wireshark or fiddler or use IE developer tools to check the header is there

User · Answer

Looks fine to me      You re sure you didn t on the settings globally or something  This is a clean installation of the beta on Windows 7  The developer tools report that the page is defaulting to IE9 Standard Mode

User · Answer

I ve posted this comment on a seperate StackOverflow thread  but thought it was worth repeating here   For our in-house ASP Net app  adding the  X-UA-Compatible  tag on the web page  in the web config or in the code-behind made absolutely no difference   The only thing that worked for us was to manually turn off this setting in IE8      Sigh    This problem only seems to happen with IE8  amp  IE9 on intranet sites   External websites will work fine and use the correct version of IE8 9  but for internal websites  IE9 suddenly decides it s actually IE7  and doesn t have any HTML 5 support   No  I don t quite understand this logic either   My reluctant solution has been to test whether the browser has HTML 5 support  by creating a canvas  and testing if it s valid   and displaying this message to the user if it s not valid     It s not particularly user-friendly  but getting the user to turn off this annoying setting  seems to be the only way to let them run in-house HTML 5 web apps properly   Or get the users to use Chrome    -

User · Answer

As an aside on more modern websites  if you are using conditional statements on your html tag as per boilerplate  this will for some reason cause ie9 to default to compatibility mode  The fix here is to move your conditional statements off the html tag and add them to the body tag  in other words out of the head section  That way you can still use those classes in your style sheet to target older browsers

[html] Why does IE9 switch to compatibility mode on my website?

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