Why Is My IE9 Website Switching to Compatibility Mode Unexpectedly?

Compatibility Mode Conundrum in IE9

Encountering an unexpected switch to compatibility mode in IE9 can be frustrating, especially when dealing with HTML5 websites. One user has reported this issue on a specific website, while other sites with similar structures render correctly. To delve into the reasons behind this behavior, let's explore the underlying causes.

As explained in the provided answer, IE9's default behavior in compatibility mode can be influenced by several factors, including:

• User-defined compatibility view settings
• Compatibility view button activity on the domain
• Automatic fallback due to previous renderer crashes
• The site's inclusion in Microsoft's compatibility view list
• Intranet status

To regain control over this behavior, website authors can explicitly set a document mode using the following:

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

Alternatively, the following HTTP header can be added:

X-UA-Compatible: IE=Edge

By setting IE=Edge, IE9 will utilize the most recent renderer version, ensuring optimal rendering performance and compatibility with modern web standards.

The above is the detailed content of Why Is My IE9 Website Switching to Compatibility Mode Unexpectedly?. For more information, please follow other related articles on the PHP Chinese website!