is filesystem::path threadsafe ? i think im seeing issues related to conversion of std::string to std::wstring (that is being used by path on windows) (so thats put blame onto string to wstring conversion) did anyone see anything like that ? if not ill try to create a small sample app that recreates the issue. code portion <similar code run in multiple threads> std::string spath("c:\\somefolder"); fs::path path(spath); // i get crash within this call seems like conversion is using static instance of codecvt and it breaks on call in (do_in) maybe its just windows codecvt issue