Somehow CUDA 9.0 for Ubuntu 16.04 is missing from nVidia’s repository still
http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1604/x86_64
Furthermore the download “deb(local)” for Ubuntu 16.04 seems corrupted, according to a friend who tried this.
I have the same problem on Ubuntu 16.04. I cannot install CUDA 9.0 (network install doesn’t have CUDA 9.0 and local install looks corrupted) but the network install works Ubuntu 17.04