Since EDGE seems to be the \"default\" browser for Windows 10, we need a way to \"force\" EDGE to open our website in IE mode or at least direct the user to open the website in
So far the articles https://technet.microsoft.com/en-us/library/mt270205.aspx and https://msdn.microsoft.com/en-us/library/Dn872481.aspx are misleading and don't fully work on my machine.
There are two options I was able to get to work.
Here is the registry keys just in case someone wants to do all this without opening group policy / IE options.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\MicrosoftEdge\Main]
"SendIntranetTraffictoInternetExplorer"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Policies\Microsoft\MicrosoftEdge\Main]
"SendIntranetTraffictoInternetExplorer"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains\google.com\www]
"https"=dword:00000001
Please, read this document updated about Enterprise Mode List for Edge: https://technet.microsoft.com/en-us/library/mt270205.aspx
As you can see there, now you have to play with Group Policies
Microsoft Edge doesn't have any other "document modes" besides its native one, so it ignores X-UA-Compatible.
I can think of three options:
Try to get your site added to Microsoft's compatibility list, so Edge asks visitors to open the site in IE. (I see you commented on Is there any method for opening specific web app by Internet Explorer from MS Edge browser? so you have probably already tried this.)
Get your site working in Edge. This may or may not be possible depending on if it uses any IE-specific features. (Does it work in Firefox or Chrome?)
Use user agent detection to display a warning message to users who aren't using Internet Explorer (look for the absence of the "Trident/" string.)