Check this link: http://superuser.com/a/171162/384610 (it's for Windows XP but works for Windows 10 as well)
Make sure the key isn't configured as hot-key in your operating system. KeePass 2 uses ALT_GR + A for 'Global auto-type'. See https://superuser.com/a/553138/384610 for how to disable this hot-key.
Gnome requires additional layouts to be activated with this command:
gsettings set org.gnome.desktop.input-sources show-all-sources trueSee https://www.reddit.com/r/gnome/comments/7jqvl9/eurkey_layout_missing_from_the_settings.
[keyboard]For a system-wide configuration, edit
/etc/X11/xorg.conf.d/00-keyboard.conf and change the value of
Option "XkbLayout" "eu"
For Windows, I created a registry file that maps the Insert key to AltGr. Making manual changes to the registry may damage your Windows installation. So if you know exactly what you are doing, and you know how to remove registry entries, you can try out the mapping. Here's to acitvate it, InsertToAltGr.reg, and here's to remove it, RemoveKeyMappings.reg. Again, only run it after having verified the registry files do what you want.
Here's a small guidance I received from someone having problem with the installation and finally managed it:
1. Windows Settings > Time and Language > Region & Language
2. In "Language | Preferred Language", click on any Language, then magically a button "Option" appears.
3. Keyboards > Add a keyboard > Add EurKey
This is a really strange phenomenon that some few people have encountered. It may be that the error tone occurs in some installations when the layout contains the capital ß (ẞ) (which was added to the German alphabet in 2017). The mere presence of the character seems to be enough for the problem to occur. I have created a version without this character, which has helped in all cases so far. You can download it here: https://eurkey.steffen.bruentjen.eu/download/windows/1.3/eurkey3s.zip