I have a DNN 5.4.2 installation.  I just upgraded from 5.3 to 5.4.2.  I run a site in two languages, where portal 0 (with home page, say, "www.mydomain.com/sa") runs in English and portal 1 (with home page "www.mydomain.com/sa/bg) runs in the second language.  After the upgrade to 5.4.2, if I directly to www.mydomain.com/sa/bg, I get a page on which the menus are in the second language, but all modules (mostly text/HTML modules) show with their English content.  Thus, the page is mixing portals 0 and 1.  On that specific page, if I click on any of the menus (which are in the second language), the pages will show up normally.  So, this is not a big problem, but seems worth looking into.

I read through the other thread.  Thanks.  The issues are different though.  Both of my languages worked ok.  The only problem that I had was that the content of the home page of portal 0 was showing up in portal 1 (even though the menus showing up in portal 1 were the menus of portal 1 - so I was surely in portal 1 but was seeing content from portal 0).

Anyway, after specifying a default start page in the Admin Site Settings everything worked ok.

So, in summary, if I don't specify a default start page in the Admin Site Settings I get content from portal 0 always when trying to get into portal 1.  Everything else works ok (menus, links, login).  After specifying a default start page the issue is gone.