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Site compatibility-impacting changes coming to Microsoft Edge

This article highlights:

  • High-impact differences between Microsoft Edge and the Chromium project, the browser engine which Microsoft Edge is based on.
  • High-impact web platform changes, which might impact browser compatibility on your site, and which the Microsoft Edge team is tracking especially closely.

For more information about other changes in Microsoft Edge, see Release notes for Microsoft Edge web platform.

The web platform is a collection of technologies used for building webpages, including HTML, CSS, JavaScript, and many other open standards. The web platform constantly evolves to improve the user experience, security, and privacy. In some cases, these changes may affect the functionality of existing webpages.

For functionality and compatibility reasons, Microsoft Edge adopts nearly all of the Chromium project's changes to the web platform. However, Microsoft retains full control of the Microsoft Edge browser and may defer or reject changes. The Microsoft Edge team decides if the change benefits browser users.

For information about upcoming Chromium project web platform changes, see Chrome Platform Status Release timeline.

High-impact changes

This table lists high-impact changes which the Microsoft Edge team is tracking closely.

Change Release Description
Insecure downloads over HTTP Future release (TBD) When a user tries to download potentially dangerous content from an HTTP site, the user will receive a UI warning, such as "Insecure download blocked." The user will still have an option to proceed and download the item. Admins can use the InsecureContentAllowedForUrls policy to specify HTTP sites for which the warning will be suppressed. Admins can use the InsecureDownloadWarnings feature flag to test the impact of this upcoming feature.
Deprecation of XSLT v159 (v157 in Edge Canary, Dev, and Beta) XSLT support represents a disproportionate attack surface, and the Chromium project which Microsoft Edge is based on has announced plans to disable and ultimately remove XSLT in a future release. See Removing XSLT for a more secure browser. As a result, you should treat reliance on client‑side XSLT as technical debt and plan migration accordingly. Microsoft Edge version 147 introduces the XSLTEnabled feature policy to support testing and transition scenarios while the Chromium project works toward deprecating and removing XSLT support. We encourage organizations to proactively test setting XSLTEnabled = Disabled to identify application dependencies and remediation requirements ahead of any future default changes or removal of the feature.
Remove _current link target v153 The non-standard _current link target, which is used to specify that a link should open in the current browsing context, is removed. See Removed _current link target in Microsoft Edge 153 web platform release notes (Sep. 10, 2026).
Deprecate unload event v152-v155 Edge 152 will introduce the new unload Permission-Policy, to allow creating unload event listeners. The default value is initially allow, but between Edge 152 and Edge 155, the default value will gradually be migrated to deny, such that unload handlers stop firing on pages, unless a page explicitly opts in to re-enable them. To explicitly enable unload event handlers, use the allow value.
Edge 152: Unload handlers will stop firing by default for 60% of page loads, unless the site explicitly enables unload handlers via the unload Permission-Policy.
Edge 154: Increases to 80% of page loads.
Edge 155: Increases to 100% of page loads.
This change is happening in the Chromium project, on which Microsoft Edge is based. See Planned deprecation of the unload event in Microsoft Edge 152 web platform release notes (Aug. 27, 2026), and Intent to Deprecate: Deprecate unload event.
Remove inline XSLT for production of SVG v147 Support for using XSLT stylesheets to transform XML data into SVG files has been removed. See Remove inline XSLT for production of SVG in Microsoft Edge 147 web platform release notes (Apr. 2026).
JPEG or PNG embedded in BMP v145 Support for embedding JPEG or PNG image data in a Bitmap image format is nonstandard, and has been removed. See Remove support for Bitmap extension to embed JPEG or PNG in Microsoft Edge 145 web platform release notes (Feb. 2026).
Externally loaded entities in XML parsing v144 Synchronous fetching of external XML entities/DTDs, which are then used when parsing under specific circumstances, has been removed. See Externally loaded entities in XML parsing, in Microsoft Edge 144 web platform release notes (Jan. 2025).

Notation for browser versions

This article uses the following notation for browser release numbers.

Notation Description
v123 The feature or change ships in Microsoft Edge version 123.
v123 (Chrome+1) The feature or change ships in Microsoft Edge version 123, which is one release after the feature or change ships in Chrome version 122.
v123 (Chrome+2) The feature or change ships in Microsoft Edge version 123, which is two releases after the feature or change ships in Chrome version 121.
Beta v123 The feature or change ships in version 123 of the Beta preview channel of Microsoft Edge.
Dev v123 The feature or change ships in version 123 of the Dev preview channel of Microsoft Edge.
Canary v123 The feature or change ships in version 123 of the Canary preview channel of Microsoft Edge.

See also