How to fix Document mode restart in IE 9

javascript asp.net internet-explorer-9 doctype
Amin Mousavi picture Amin Mousavi · Jun 19, 2012 · Viewed 31.2k times · Source

I have a problem with opening my website in IE9. When I try to open my site I get this error in dev tools:

HTML1113: Document mode restart from Quirks to IE9 Standards

I googled and found an answer that suggested to use this:

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

or 

<meta http-equiv="X-UA-Compatible" content="IE=IE9" />

...but these do not work and I get the following message this time:

HTML1115: X-UA-Compatible META tag ('IE=Edge') ignored because document mode is already finalized.

What is my problem? I read several articles like IE’s Compatibility Features for Site Developers by Microsoft and traced my site with Determining IE9’s Document Mode flowchart and use all suggestions relating to !doctype on these sites but no-one could solve my problem and my IE engine reset after the page opened.

I develop my site with ASP.NET 4 on Windows Server 2008. How can I fix this issue?

Answer

Andrew Андрей Листочкин picture Andrew Андрей Листочкин · Jun 19, 2012

One solution that should always work is to put your X-UA-Compatible in HTTP headers. Also, your <!DOCTYPE> should be specified at the top of your HTML document (<!DOCTYPE html> is the easiest one).

If you put your X-UA-Compatible declaration inside the meta tag you can run into the following problems:

  1. X-UA-Compatible is ignored unless it's present inside the first 4k of you page. If you put it somewhere in the bottom of your head section (or in the body) move it to top. The best place for it is right after encoding and language declarations.

  2. X-UA-Compatible is ignored if it's put inside IE conditional comments. For example:

    <!--[if IE]>
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<![endif]-->

    In this case you should remove conditional comments.

  3. Also, you shouldn't have any text before the doctype declaration. If you've got any HTML comments there, for example, the IE will switch to quirks mode.

  4. Finally, check if you're viewing this site from the intranet. By default Compatibility View is enabled for Intranet sites.

I suggest set X-UA-Compatible header for you page and then see if your site is still switching to quirks mode. In that case you should check your markup and try to fix any HTML validator errors until it's back to Standards Mode.

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