I had Multilingual DNN 7.1.0 by Two languages and Default language was "Farsi" and secondary language was "English" First Upgrade was to 7.2.2 and First Problem happen:

1. Default language change to "English" and I never could change it back to "Farsi"

Again I Upgrade from 7.2.2 to 7.3.1 and New Problem happen!:

2. Now Language DropDown Totally not working and you can not change language from "English" to "Farsi" and I have to Restore my backup and never upgrade for ever!!!!

How can Solve these two big problem?