OK, I understand that this is happening because of schema violation, but nevertheless, I still need some advices or tips, how to avoid getting into trubles when upgrading the servers. Is there an easy way to get rid of the problem, but still using this type of suffix with country value longer that 2 characters?
Slapcat and fix the values; the 2 character abbreviations are an ISO standard you can download. Modify your application to only accept legitimate country codes.
http://www.iso.org/iso/country_codes/iso_3166_code_lists/english_country_names_and_code_elements.htm