sudo apt-get install --reinstall iceweasel iceweasel-l10n-de
root: apt-get install --reinstall iceweasel iceweasel-l10n-deGerman-Site:http://www.camp-firefox.de/sprachpaket
Deutsch (DE) language Pack could not be installed because it is not compatible with iceweasel 31.2.0
Addon: Locale-Switcher