The Intel® Quartus® Prime software version 18.1 requires additional libraries to be installed for Ubuntu 18.04 LTS.
To work around this problem, make sure the following libraries are installed for Ubuntu 18.04 LTS:
libc6:i386, libncurses5:i386, libxtst6:i386, libxft2:i386, libc6:i386, libncurses5:i386, libstdc 6:i386, libc6-dev-i386, libxft2, lib32z1, lib32ncurses5, lib32bz2-1.0, libpng12, libqt5xml5, liblzma-dev
Since libpng12 is no longer available via the apt-get method, download and install libpng12 from this location https://packages.ubuntu.com/xenial/amd64/libpng12-0/download
This information is scheduled to be updated in the Intel® FPGA Software Installation and Licensing document in a future release.