Microsoft Will End IE Mode Support by 2029

The company will retire the legacy MSHTML rendering engine, requiring enterprises to modernize remaining applications.

Updated on Sept. 21, 2026 in Internet

Bold flat-color editorial illustration showing a stack of server-rack volumes, evoking the institutional shift of retiring legacy browser architecture. — Microsoft announced it will terminate support for Internet Explorer Mode by 2029, finalizing the retirement of the legacy MSHTML rendering engine. 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 confirmed that support for Internet Explorer Mode will conclude by the end of 2029. This upcoming retirement marks the final removal of the legacy MSHTML engine from modern Windows environments.

Why it matters

Ending support for IE Mode forces organizations to complete the transition of legacy web applications that currently rely on aging browser architecture. This shift allows the company to fully move away from technologies dating back to the early web era.

IE Mode functions by leveraging the MSHTML engine from Internet Explorer 11 within a modern Chromium browser wrapper. This legacy rendering environment has been a fixture for enterprise compatibility since the engine's original introduction in version 4.0.

The players

Microsoft

A global technology company that develops the Windows operating system and the Chromium-based Edge browser.

The details

IE Mode allows modern Windows browsers to render older websites by calling upon the MSHTML engine, also known as Trident. By retiring this component, Microsoft is eliminating a core dependency that has persisted since the MSHTML 7.0 engine era. Organizations currently utilizing these legacy applications are encouraged to use the App Assure service, which provides compatibility assistance to help teams modernize their software stacks before the support window closes.

2015: Microsoft officially retired support for Internet Explorer.
2021: Microsoft first announced the 2029 retirement timeline for IE Mode.
September 2026: Microsoft issued deprecation reminder notice MC1473151.
End of 2028: Deadline for Microsoft to issue a mandatory one-year warning notice.
End of 2029: IE Mode support officially ends.

The Tech Race

This decision follows the industry-wide push to modernize enterprise workflows and eliminate reliance on non-standard browser rendering engines. It aligns with the long-term roadmap to unify the web experience under the Chromium standard, effectively closing the chapter on the Internet Explorer 11 legacy.

Enterprise users still running legacy internal portals via IE Mode will need to transition those applications to modern browser standards over the next several years. Organizations requiring technical migration support should engage with the App Assure service to ensure their workflows remain compatible with future Windows updates.

The takeaway

The end of IE Mode signals that the final transition away from legacy Trident-based web rendering is now set for 2029. IT administrators should track the required one-year formal warning notice due by the end of 2028 to finalize their application migration schedules.