Comment 9 for bug 1900917

Pico,

Thanks for validating this; I really appreciate you taking the time to test.

To summarize...

1. The installer auto-generates a /boot/grub/grub.cfg
2. If the installer sees vmlinuz.efi in the /casper directory of the ISO...
   It generates a grub.cfg file that references "vmlinux<kernel-version>.efi.signed"
   But "vmlinux<kernel-version>.efi.signed" does not exist
3. If the installer does NOT see vmlinuz.efi in the /casper directory of the ISO...
   It generates a grub.cfg file that references "vmlinux<kernel-version>"
   And "vmlinux<kernel-version>" does exist

With vmlinuz.efi...
- Linux Mint and Ubuntu fail to boot into the installed OS
- Pop_OS! installs successfully

Without vmlinuz.efi...
- Linux Mint and Ubuntu boot successfully into the installed OS
- Pop_OS! fails to install