Admins, You've Been Warned: The Clock Is Ticking on Edge's IE Mode
The Register, Friday, September 18th, 2026
Legacy web apps have guaranteed shelter only through 2029, and Microsoft warns modernization projects can take years.
Microsoft has reminded administrators via the Microsoft 365 admin center that Internet Explorer mode in Edge is guaranteed support only through the end of 2029, and that it is time to start legacy migrations.
IE mode uses the Trident MSHTML engine from Internet Explorer 11 and permits elements such as ActiveX controls, though other IE functionality like custom toolbars is unsupported.
Microsoft has promised one year's notice before retirement, and the feature is unlikely to stop working the moment support ends, but organizations that depend on it would face security, compatibility and compliance risk.
The company's own warning is that application modernization projects can take years depending on the number and complexity of dependencies, so early planning reduces later disruption.