Microsoft has once again reminded enterprise IT administrators via the Microsoft 365 admin center that the built-in Internet Explorer (IE) mode in the Edge browser will be supported at least until the end of 2029. The company has committed to providing at least one year's notice before officially ending support and urges enterprises that still rely on websites or applications compatible only with the IE kernel to begin modernization efforts as soon as possible.

IE mode allows enterprises to continue running legacy websites and applications based on the old IE kernel within the Edge browser, utilizing the Trident MSHTML engine used by IE11. This means it still supports outdated technologies like ActiveX controls, although some IE-specific features, such as custom toolbars, are no longer supported. The continuation of this mode is primarily due to many enterprises having critical business systems built on such outdated technologies, making replacement and migration costly and time-consuming. The IE11 desktop application officially stopped support on June 15, 2022, but IE mode has been retained as a transitional solution.

Microsoft's notification clearly states, "Application modernization projects may take years to complete, depending on the number and complexity of dependencies, so early planning can reduce the risk of disruptions later on." The company provides three specific action recommendations for enterprise IT departments: first, create a dependency list by reviewing the existing "Enterprise Mode Site List" and current usage to identify critical business websites and applications that truly need IE mode support; second, evaluate modernization paths to determine whether each application should be updated, migrated, replaced, or restructured; third, if compatibility issues arise, enterprises can apply for the Microsoft App Assure program, which offers free assistance to eligible customers. Microsoft also emphasizes that this notification is merely a heads-up and does not involve any changes to functionality, and enterprises do not need to take immediate action; existing IE mode configurations will not be affected.

This support commitment covers multiple cloud environment versions, including global, GCC, GCC High, and DoD (Department of Defense). Notably, IE11 itself is still provided with the Windows 10 IoT Enterprise LTSC 2021 version, which will continue to receive official support until 2032. This means that the deactivation of IE mode in Edge may occur before the end of the corresponding operating system's lifecycle, and the two timelines are not fully synchronized, requiring enterprises to evaluate them separately when formulating migration plans.

Microsoft also reminds that after IE mode stops being supported, any systems continuing to run on the old kernel will no longer receive official security updates or compliance guarantees. Enterprises will then need to bear the risks of security vulnerabilities, compatibility failures, and compliance audit risks that arise, although functionality will not immediately fail—this "gradual loss of support" characteristic may lead enterprises to underestimate urgency and continue to delay migration progress.

From an industry chain perspective, Microsoft's early migration warning issued over three years in advance essentially signals demand for the large-scale enterprise legacy system transformation market: on one hand, professional service providers, system integrators, and cloud migration tool vendors focused on application modernization, code migration, and system restructuring will gain continuous orders from this long-term, certain migration demand; on the other hand, Microsoft's own involvement in the migration process through free assistance programs like App Assure also strengthens enterprise customers' ties to the Edge and Azure cloud ecosystem, indirectly driving its cloud computing and productivity tools business. In terms of funding, enterprises that initiate migration assessments early and seize professional service capacity will be able to spread transformation costs more comfortably, while those that choose to delay until the last year of the 2029 notification window may face multiple pressures, including tight migration service supply, project scheduling delays, and concentrated security compliance risks.

Source: Public Information