See https://gitlab.com/eidheim/Simple-Web-Server/blob/db24254c96225c65af4637d387eb638e95ed313d/utility.hpp#L369 This should be "Dec" and not "Des", which probably stands for the Norwegian word Desember. Also to add the Date header I just use strftime: ``` char date[32]; { auto t = time(nullptr); auto tm = gmtime(&t); std::strftime(date, sizeof(date), "%a, %d %b %Y %H:%M:%S GMT", tm); } header.emplace("Date", date); ``` However you might have to set the locale to en_US if the program is running in a different locale.