OSError: libmpi_cxx.so.40: cannot open shared object file: No such file or directory

Hi @3356383019, your original post above said you were on JetPack 5 - which is based on Ubuntu 20.04, and would have installed libmpi_cxx.so.40. If you are in fact on JetPack 4 and Ubuntu 18.04, then you should install one of the PyTorch wheels built for JetPack 4 instead.