Language Setting in OH2 leads to an empty dash

Hey!
I just installed the OH2 “online” package on debian. After setting the language and locale setting to “DE” in the GUI the dash is empty. Just showing “Welcome to OpenHAB 2.0” and then nothing …

Can anybody tell me, where to find the config file to set it back (and hopefully have original dash)?

Thanks!

May this message belong to the problem:

2016-09-22 23:00:15.973 [ERROR] [.glassfish.hk2.osgi-resource-locator] - FrameworkEvent ERROR - org.glassfish.hk2.osgi-resource-locator