Microsoft Edge browser testing notes

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Windows 10 is deprecating the old Microsoft Internet Explorer browser in favor of the new Microsoft Edge, with an updated rendering engine that is significantly more compatible with other modern browsers.

Since many MediaWiki developers run on Mac OS X or GNU/Linux systems, a few notes about compatibility testing with Edge may be helpful.


The Edge team maintains a changelog for each release and preview build; this covers web platform features but doesn't always mention rendering bug fixes.

Upcoming web platform/DOM features are listed on the Platform Status page.


Getting Edge[edit]

Edge is bundled with Windows 10, which is widely available but not freely redistributable.

  • Virtual machines: Microsoft has made Windows 10 + Edge VMs available for free. You can download and install these on your computer for testing. As of April 2016, both the "stable" Edge 13 and the "preview" Edge 14 are available. See #Versioning below for more about the release cadence, and #Windows Insider preview builds for how to get prerelease versions on bare-metal.
  • Cloud: Various companies provide cloud-based cross-browser testing that support Microsoft Edge. All of these allow access to a live viewport within your browser to a remote VM in the cloud:

Filing bugs[edit]

As of April 2016, Microsoft has set up a separate public EdgeHTML issue tracker for bugs and feature suggestions in the browser engine; this should be used instead of the old general Microsoft Connect. You will need log in with a Microsoft account (same as Xbox Live, Hotmail, or anything else using Microsoft Passport auth). Include a link to any bug reports you file there on the Phabricator side and vice versa to make sure we don't get lost. You may also want to add them to User:Catrope/IE bugs.

If you get feedback on your bug on the EdgeHTML tracker, be sure to update the Phab bug with status.

Debugging tools[edit]

The 'F12 developer tools' on desktop/tablet are pretty good, comparable to the the debuggers in Firefox, Chrome, and Safari/WebKit.

On mobile, the remote debugger is not yet available.


Good question. Anyone know anything? :)


IE/Trident heritage[edit]

The Edge engine is based on MSIE's older Trident engine, but removes a lot of old IE-only features, adds a lot of modern stuff, and generally makes a bajillion improvements.

Old IE-specific workarounds should not simply add checks for Edge -- as much as possible, treat Edge like any other modern browser, and introduce checks around specific feature availability or bug detection if possible.

Note that IE 11, while still included in Windows 10 as an optional tool, is no longer receiving bug fixes other than critical security issues. Any bugs found in IE should be double-checked against Edge, but bugs should only be filed with Microsoft for those that remain in Edge.


There are significant differences from Internet Explorer:

  • Edge is only available on Windows 10. There is no version of Edge for Windows 7/8/8.1.
  • Windows 10 and Edge are updated together; Edge's rendering engine is a system component.
    • It can be assumed that most Windows 10 users will receive timely updates, but there may be stragglers.
  • Windows 10 is updated much more aggressively than older releases of Windows, with multiple major updates planned per year.
    • August 2015 RTM: Edge 12 / Windows build 10240
    • November 2015 "1511 update": Edge 13 / Windows build 10586
    • June(?) 2016 "Summer update": Edge 14 / (Windows build to be determined)
  • Beware of old testing VMs! If you have a test VM that's still on 10240 you may need to let it update to get behavior consistent with what your users see. Updated VMs were released in April 2016 for Edge 13 (stable) and 14 (preview).

Windows Insider preview builds[edit]

If you want to test preview versions of Edge on bare metal instead of using the VM downloads, any Windows 10 system can opt in to the "Windows Insider" program to receive preview builds. However there are some gotchas:

  • There may be a delay of several hours from the opt-in before preview updates appear in Windows Update. This is extremely annoying when setting up a new test machine.
  • It is possible to revert to the current release, but consider using a spare machine or cloning an existing VM in case of explosions.
  • There are multiple "rings" of update schedules; select the "fast" ring to get the latest updates.
  • Occasionally preview features are broken or incomplete! Beware that some end-users will be using these Windows 10 Insider preview builds; so breakages unique to those versions are possible.

Device families[edit]

The same Edge engine is used on multiple Microsoft platforms, kept more or less in sync:

  • The exact same browser is used in both 'desktop' and 'tablet' modes (Windows 8/8.1 had separate 'Desktop' and 'Modern' IE variants)
  • Windows 10 Mobile for phones uses the exact same Edge rendering engine and shell app (UI layout depends on screen size)
  • Xbox One also includes the Edge browser