Ubuntu Jammy Desktop ISO installer fails to find live filesystem on Mac Pro 2012 (Mac 5,1 Westmere)

[Rodney Lott]

I used a USB stick tool called Mac Linux USB loader to create a bootable USB stick so that I could install Ubuntu Jammy Desktop on my Mac Pro 5,1 Westmere (circa 2012). I was able to do the same installation and install Ubuntu Focal Desktop on my Mac Pro without issues, but the Ubuntu Jammy ISO would not get to the main installer. After getting past the GRUB menu and the Ubuntu splash screen, it fails with a screen full of messages saying:

/init: line 49: can't open /dev/sr0: No medium found

After this stream of messages, it asks to attempt interactive netboot:

Unable to find a medium containing a live file system
Attempt interactive netboot from a URL?
yes no (default yes):
Two methods available for IP configuration:
  * static: for static IP configuration
  * dhcp: for automatic IP configuration
static dhcp (default: dhcp):
[Asks for vlan ID and ISO URL, etc. ...]
[Connects to cdimage.ubuntu.com and starts downloading jammy-live-server-amd64.iso ...]
[Download completes ...]
Unable to find a medium containing a live file system

BusyBox v1.30.1 (Ubuntu 1:1.30.1-7ubuntu3) built-in shell (ash)
Enter 'help for a list of built-in commands.

(initramfs) ls /dev/sd*
/dev/sdb1 /dev/sdb /dev/sda2 /dev/sda1 /dev/sda
(initramfs) cat /proc/version_signature
Ubuntu 5.15.0-23.23-generic 5.15.27

[Rodney Lott (rlott3869)]

If I boot into the Ubuntu Focal installation, here's the additional information about my hardware (see attached lspci output log).

Let me know what other information you require.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Libera.chat.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1967753/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Seiichi Nakashima (ubuntu-linuxer)]

Hi,

Today I boot up jammy-desktop-amd64.iso from grub.
My 40_custom file

menuentry "Ubuntu 20.04.4 ISO" {
    set isoimg="/iso/ubuntu-20.04.4-desktop-amd64.iso"
    loopback loop (hd1,msdos1)$isoimg
    linux (loop)/casper/vmlinuz boot=casper toram iso-scan/filename=$isoimg
    initrd (loop)/casper/initrd
    }

menuentry "Ubuntu 22.04 ISO" {
    set isoimg="/iso/jammy-desktop-amd64.iso"
    loopback loop (hd1,msdos1)$isoimg
    linux (loop)/casper/vmlinuz boot=casper toram iso-scan/filename=$isoimg
    initrd (loop)/casper/initrd
    }

ubuntu 20.04.4 boot up fine.
but jammy-destop-amd64.iso is display same messages forever.
and I could not Ctrl-C, then I reset PC.

init: line 49: can't open /dev/sr0: no medium found