Thread:Project:Support desk/No Messages of my extension in Special:Allmessages/reply (3)

Yes, especially that part, should be platform independent (and more importantly, linux is the primary target platform [wikipedia runs on unbuntu!] so any cross platform issues would probably appear when using windows not linux).

Debian's mediawiki package likes to move files around a lot (or at least they used to, I'm not sure if they still do). If you downloaded mediawiki via apt-get install it could be something to do with that. [My next guess after that would be something gone wrong with the i18n cache system]