FYI: If we change it, we need to check all usages of the login for security etc. It might be used somewhere and not proper escaped as one was assuming it contains only [a-Z0-9-_]

@tsteur is it possible to check if it's a character or a special char?
Didnt found something until yet...i use currently \p should contain all characters but does not...

[\p{L}0-9äöüÄÖÜßé]

If this is just about umlauts as a temporary fix we should be able to just add äöüÄÖÜßé to the allowed characters. It will of course not solve it entirely but would maybe make things easier for some users :) I read about \p{L} but not sure which letters it actually contains and whether there are possible security issues etc.

@tsteur depends on the charset...used it somewhere for LDAP regex, but also didnt contain all wanted chars :-)

Seems to be a bit complicated....

http://www.regular-expressions.info/unicode.html#script

if we can fix this in core by adding umlauts to the regex then maybe we should just do this for now?

We should just still leave the issue open or create a follow up issue to also fix this for other letters. People will most likely have this problem again very soon

Is there any workaround for this?
In combination with LoginLdap and a company-wide Active Directory, this is kind of bad. :|

@ChristianGfK try this workaround (NOT tested)

Replace this line https://github.com/piwik/piwik/blob/master/core/Piwik.php#L592

&& (preg_match('/^[A-Za-zÄäÖöÜüß0-9_.@+-]*$/D', $userLogin) > 0))

Thanks @ThaDafinser, I'll have a look at doing that when I take the 2.16 plunge later. :-)

as we have so many German users, let's do the quick fix of allowing german characters in 2.16.x 👍