We were doing some investigation into user sessions on our consumer facing sites and came across something that really disturbed me.

On an average day, we have ~140k visitors to our sites who bother sending in a user agent string (most bots and crawlers who identify themselves don't get their session information recorded, so the vast majority of this is real people).

  • Around 45000 of these are Windows 7 (UA contains 'NT 6.2'), about 4000 of which say the browser is IE7.

  • Around 5000 of the total are Windows 8 (UA contains 'NT 6.2').

  • Around 200 of those Windows 8 user sessions say they're running IE7!

Now, Windows 7 originally shipped with IE8, and you cannot install IE7. Windows 8 came with IE10 and you cannot install IE7.

I know how this can happen; in IE9 and IE10, either of these can cause the browser to behave and identify as a different version.

  • The user manually changes the browser mode via developer tools. (Highly unlikely that 4% of our users even know what developer tools are, let alone regularly toggle the browser mode.)
  • The user goes to the ToolsCompatibility View dialog and checks the "Display all websites in compatibility mode" checkbox.

The question is: Why?

The only possible explanation I have for an ordinary user willfully carrying out this abomination is that some external authority figure told them to do or did it for them: a systems admin did it for handling the stereotypically crappy business intranet/portal site or some 3rd party website they regularly visit and depend upon (a bank? perish the thought) popped up a page saying they would have to take the following, totally secure steps to consume their awesome application.

Even with that totally plausible scenario in mind, 10 and 4 percent for Windows 7 & Windows 8 users respectively seems terribly high.

Is there some other process, like an internal help or troubleshooting prompt that IE itself makes, to tell the user to permanently enable compatibility mode? Is there some other way that IE can automatically change this setting? My curiosity is killing me on this one.


Ensure your pages implement a proper X-UA Compatibility Meta Tag.

Something like <meta http-equiv="X-UA-Compatible" content="IE=7" /> might be causing what you're seeing.

Some related info over on StackOverflow: How to force IE10 to render page in IE9 document mode

Additionally, IE's compatibility modes can be forced by domain policies, so the users have no control over it.

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  • So we have a two technology stacks at the moment, deprecating the old and migrating to the new. The new stack pages all have the IE=edge declared and the old stack pages have no declaration at all. Should have mentioned that in the question... but even with the edge declaration, we have verified a few cases of NT 6.2 with IE 7 UA strings. Thus me turning here. – Patrick M May 4 '13 at 5:34
  • Updated my answer a bit. Re: Domain Policies. – Ƭᴇcʜιᴇ007 May 4 '13 at 19:02
  • Oh snap, I hadn't considered that. Puts a new angle on my 'IT admin does it for them' scenario. Do you have a reference for how that's done? – Patrick M May 4 '13 at 20:59

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