Microsoft Will End IE Mode Support by 2029

The company has confirmed that its legacy Internet Explorer compatibility mode will be retired in 2029.

Updated on Sept. 21, 2026 in Internet

Isometric editorial illustration of a monolithic archway on a plinth, symbolizing the sunset of legacy web engine technology. — Microsoft has confirmed it will officially retire its Internet Explorer compatibility mode by the end of 2029, forcing organizations to modernize legacy applications. AI Illustration. Upload story photo >

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Will your organization successfully replace all legacy applications before IE Mode support ends in 2029?

Microsoft has announced that it will officially end support for IE Mode by the end of 2029. This move marks the final phase in removing the company's ancient web engine technology from modern systems.

Why it matters

The retirement of IE Mode forces organizations to modernize legacy applications that still rely on the aging MSHTML Trident engine. Ending this support allows Microsoft to fully eliminate outdated web technology from its platforms.

IE Mode currently utilizes the MSHTML Trident engine, which was introduced in version 4.0 of Internet Explorer and reached version 7.0 in later iterations. The system enables modern Windows browsers to render legacy pages by running the older engine within a Chromium shell.

The players

Microsoft

The Redmond-based technology corporation provides the Windows operating system and the Microsoft 365 suite used by organizations worldwide.

The details

Microsoft confirmed its plan via admin notice MC1473151, reminding organizations that the compatibility feature will be phased out. The company provides the App Assure service to help businesses transition their dependent software before the deadline.

Microsoft officially retired support for Internet Explorer in 2015.
The 2029 retirement timeline for IE Mode was first announced by Microsoft in 2021.
Microsoft issued a deprecation reminder notice, MC1473151, in September 2026.
A formal one-year warning notice will be issued by the end of 2028.
Support for IE Mode is scheduled to end by the end of 2029.

The Tech Race

This transition marks the final step in removing legacy web standards that have persisted long after the 2015 retirement of Internet Explorer. The industry shift toward modern browser engines replaces outdated rendering methods to improve security and performance across the internet.

Organizations currently relying on legacy tools for business operations must migrate their applications to modern browsers to avoid workflow disruptions. Employees using older, internal-only web portals should prepare for potential compatibility issues as the support deadline approaches.

The takeaway

Businesses should audit their internal software inventories now to identify dependencies on the aging Trident engine. Proactive migration reduces the risk of operational failure when support for these legacy technologies officially concludes.