I recently went through this. We have a somewhat older ASP.NET website, that doesn't want to work with Internet Explorer 11. But more and more of our external users are getting new PCs that come with IE 11 installed. I had made changes to the web site so that it would work. I tested it as thoroughly as I could and then pushed it out to production, but that turned out to be a disaster. Not only did it not work for IE 11, if didn't work for any browser. I spent an hour or so trying to get it to work, and finally decided to rollback. Better that users using IE 11 couldn't use the site, than no one at all couldn't use it.

It wasn't a satisfactory choice, but I felt it the only one open to me. I'm still puzzled as to why it didn't work, because it worked perfectly in testing. And unfortunately for me, as often happens in my job, other more urgent priorities have come up requiring my attention. This website/IE11 issue has been pushed to the back burner. However, I intend to put up a staging site on a server that's not visible to the outside world, where we can test it again, before putting it out for the rest of the world to use. One that will mirror the production web server as closely as possible.

When I have the time to get back to it.