Maybe it's more a missing feature, than a bug:
A blank Easy Admin Installation, with some default YAML configuration (no custom CSS or JS), looks like this in IE11:

The console also outputs some JS issues:
SCRIPT1002: Syntaxfehler
app.js (26,20604)
SCRIPT5009: "$" ist undefiniert
website.com (359,9)
SCRIPT5009: "jQuery" ist undefiniert
en.js (3,13)
This makes in impossible to use EasyAdmin in IE11 (which is unfortunately still required, for some projects).
@ArminVieweg I'm afraid I must close this for the same reasons explained in this comment:
I'm sorry, but we don't intend to support any IE browser version. We use modern CSS and JavaScript features which are not supported on IE, so it's impossible to make it work.
In any case, we're not judging you or your project. We know sometimes certain apps must be used for some reasons. So using IE, even if it's legacy compared to other browsers, may be fine in your case 馃憤
Hey. Thanks for the response. I've asked the best Frontend guy I know and he did it.
Basically two polyfills and a small change when including js files are required to make EAB work in Internet Explorer 11.
Would you consider to merge a PR for this, when I provide it?
I thank you for your proposal, but I prefer to not include that in the bundle. The reason is that, even if it may look like a small change now, it forces you to take that into account forever, so it may affect new features (e.g. #2670).
I understand, nevermind.
Hey. Thanks for the response. I've asked the best Frontend guy I know and he did it.
Basically two polyfills and a small change when including js files are required to make EAB work in Internet Explorer 11.
Would you consider to merge a PR for this, when I provide it?
I'm interested in your fix cause I would like to run EasyAdmin on IE11 for a customer. Do you have it ? Thx !
I'm interested too @ArminVieweg 馃憤 please :)
Actually, this fix works... But the performance is very very bad!
In some (default) list views it takes up to 5-6 seconds until javascript applied all the missing functionality.
The performance is so bad, that I have to find another solution. It is so stupid to optimize web applications for IE... But I think about taking the original AdminLTE styles and adjust them a little bit. Not sure how much work this will be. According to the description of EAB, it is based on AdminLTE.
What hurts IE most is the display: grid usage. And native CSS variables (--var).
I'm interested too @ArminVieweg can you explain how you fix it please :)
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I'm interested in your fix cause I would like to run EasyAdmin on IE11 for a customer. Do you have it ? Thx !