For the 64-bit releases of Linux Mint 19 there was an issue with ubuntu-system-adjustments preventing EFI installations from completing successfully when connected to the Internet. This has been fixed in the repositories and new ISOs have been made available.
- New ISOs are on the download page and have v2 at the end of the filename (e.g., "linuxmint-19-edition-64bit-v2.iso").
- If you have already installed Linux Mint 19, you don't need to do anything as this issue only affects new installs using the old ISOs.
- If you haven't installed Linux Mint 19 yet but you have an old ISO (without v2 at the end of the filename) you can safely install from that if you just make sure your computer is not connected to the Internet during installation.
- This issue doesn't affect 32 bit installs.