GNOME Bugzilla – Bug 741833
special characters in passwords don't work with non en_US keyboard layout
Last modified: 2016-01-12 22:43:13 UTC
when you have a non English keyboard layout, there seems to be an issue with special characters in passwords. Obviously gdm always uses the en_US keyboard layout and thus you cannot use passwords with special local characters. see https://bugzilla.redhat.com/show_bug.cgi?id=1164283 and https://bbs.archlinux.org/viewtopic.php?id=188509
You can configure keyboard layouts for the login screen in System Settings -> Region & Language, or with 'localectl'.
"Invalid" is not a correct resolution. In 3.14, setting the language in the system settings didn't affect the login screen. However, in 3.18 the bug is fixed, and the system settings does affect the login screen again.