Login screen is not loaded when Business Central run on non-suported localizaton of OS

I installed BPMS 6.4.0.CR1 to Eap6 with no problems and then started server. When I tried to login into BC, I get server error windows instead login page (see screen shots). I tried also with deploying it from deployable zip with same result for Eap6 and Eap7. On BPMS 6.4.0.ER3 was login page correctly loaded.
When I changed Firefox property intl.accept_languages from cs, en-us, en to en, cs, en-us and clear Firefox memory an reload login page, then I was able to login into BC. I also tried to change property general.useragent.locale form cs-CZ to en-US but this didn't help.
I tried it in Chrome and I get same result. When I set in Chrome English as default language, then login page was loaded without an error.
I'm using Fedora 24 with cs-CZ localization. When I tried to reset localization to en-US everything works correctly, without any errors. I also tried to add to intl.accept_languages value cs and still work fine on en-US localization.