I am not a Plesk for Windows expert, but here is my guess: According to your screenshot there are no tables in your database ("Tables: 0"). When you export no tables, probably there are no tables being exported. When you re-import no tables, it is very likely that there will be no dump contents in the dump file, because there have not been any tables in the database. Leading to the conclusion that a ZIP-file that does not have any tables in it does not have anything in it to import. For that reason you are seeing "There are no files in the uploaded ZIP archive.".