IE renders webpages in Quirks mode

Wednesday, March 27, 2019

IE renders webpages in Quirks mode

These are the reasons that IE would render a webpages in Quirks mode (IE5):

X-UA-compatible meta tag

For example, setting the tag in the <head> section of the HTML file:
<head>
<meta http-equiv="x-ua-compatible" content="IE=5">
</head>

X-UA-Compatible HTTP header

For example, if the X-UA-Compatible header is configured in web.config:
<system.webServer>
    <httpProtocol>
      <customHeaders>
        <add name="X-UA-Compatible" value="IE=5" />
      </customHeaders>
    </httpProtocol>
</system.webServer>

Or is set in the C# code:
HttpContext.Current.Response.Headers.Set("X-UA-Compatible", "IE=5");

The website is added into the Compatibility View Settings of the IE browser

To do that, load the URL of the website in IE. And then click the Tools icon (the gear icon) and select Compatibility View settings. Click the Add button to add the URL.

Microsoft Compatibility List

If the website is in the Microsoft Compatibility List, and the Use Microsoft compatibility lists option is checked in the Compatibility View Settings (see above).

To get a latest Microsoft Compatibility List, visit https://docs.microsoft.com/en-us/previous-versions/windows/internet-explorer/ie-developer/compatibility/gg622935(v=vs.85)#updating-the-cv-list

Intranet website

If the website is inside Intranet and the Display intranet sites in Compatibility View option is checked in the Compatibility View Settings.

To add or check if the website has been added into intranet, go to Internet Options|Security. Click the Sites button, then click the Advance button.

Tips, Tricks and Tools

Wednesday, March 27, 2019