If you’ve stubbornly resisted upgrading Internet Explorer on an older PC, you might be forced to act soon. (Of course, if you work for a company that has stubbornly insisted on making you use an ancient version of IE, this is good news.)

Starting January 12, 2016, Microsoft is changing its list of supported Windows configurations. Effective that date, the company said in an announcement today, “only the most recent version of Internet Explorer available for a supported operating system will receive technical support and security updates.”

Support for the five-year-old Internet Explorer 8 will be dropped completely for Windows desktop and server releases. On mainstream PCs, Internet Explorer goes into the same bucket as Windows XP, which reached its end-of-support date in April 2014. Microsoft will not release security updates for Internet Explorer 8 on desktop versions of Windows after the first Patch Tuesday of 2016 (security updates for Internet Explorer 8 will continue to be available after the cutoff date for a handful of embedded operating systems).

That’s likely to affect a lot of people: Net Applications says IE 8 is the most popular single browser version worldwide, installed on more than 20 percent of all PCs running a desktop OS, including many that are still running Windows XP.

StatCounter says roughly 6 percent of all web traffic uses that ancient browser.

Internet Explorer 9 and 10, which have a combined share of more than 15 percent, will be supported only on three older platforms, where later versions can’t be installed.

IE 9 is supported in Windows Vista (SP2 or later) and Windows Server 2008 (also SP2 or later). Windows Vista will reach its end-of-support date in 2017.





IE 10 is the only supported version for Windows Server 2012.

That leaves Internet Explorer 11 as a required upgrade for all PCs and devices running Windows 7, Windows Server 2008 R2, and Windows Server 2012 R2. (It’s installed by default with Windows 8.1.) Excluding surviving Windows XP machines, that means about 98 percent of all Windows PCs in use worldwide will be required to have Internet Explorer 11 installed to continue to receive security updates.

As with Windows XP, there’s no Redmond “kill switch” for older IE versions. If you or your business want to continue using an older, unsupported browser configuration, nothing except common sense will prevent you from doing so.

For businesses that still rely on internal apps that require older Internet Explorer versions, Microsoft is strongly recommending Enterprise Mode for Internet Explorer 11, released in April 2014. Skip the rambling five-paragraph introduction and look to the middle of today's IE blog post:

"Enterprise Mode…offers enhanced backward compatibility and enables you to run many legacy web apps during your transition to modern web standards. Today we are announcing that Enterprise Mode will be supported through the duration of the operating system lifecycle, to help customers extend their existing web app investments while staying current on the latest version of Internet Explorer. On Windows 7, Enterprise Mode will be supported through January 14, 2020. Microsoft will continue to improve Enterprise Mode backward compatibility, and to invest in tools and other resources to help customers upgrade and stay up-to-date on the latest version of Internet Explorer."

If that's not an option for a large business or government agency, they might be able to arrange for pricey custom support contracts like those negotiated by some XP laggards. But most businesses will have no legitimate alternative when the end-of-support date rolls around.

This change shouldn’t come as a surprise to anyone, and it's a relatively leisurely schedule. The new, more rapid cadence at Microsoft makes it much more difficult to maintain compatibility with older versions. Moving the vast majority of the customer base to a single supported platform is essential if Satya Nadella's changes in the engineering organization are going to be truly capable of keeping up with aggressive competitors.

In an unrelated backward-compatibility development, Microsoft also announced today that .NET Framework 4.5.2 will be the only supported version for .NET 4 applications: