Unable to boot Live USB on Mac

[Scott]

Live USB boot reaches grub but fails some time after and fails to completely boot on Macbook Pro 11,3 with Ubuntu 20.04.3

After selecting 'Ubuntu' or 'Ubuntu with safe graphics' the splash screen shows, and after a while the screen is filled with lines of `/init: line 49: can't open /dev/sdb: No medium found` with one line at the bottom of `Unable to find a medium container a live file system. Attempt interactive netboot from a URL?`

Booting with debug option from grub does not give keyboard access. I have attached a photograph of the output at boot time to this ticket as extracting logs from the system does not seem possible.

Full hardware specs of the exact model can be found here: https://everymac.com/systems/apple/macbook_pro/specs/macbook-pro-core-i7-2.5-15-dual-graphics-mid-2014-retina-display-specs.html

The iso file used is ubuntu-20.04.3-desktop-amd64.iso

The SHA256 of the downloaded iso file and MD5 sum of all files on the USB using the included md5um.txt have been confirmed OK.
All USB ports on the machine, and multiple USB devices have been tested.
The Live USB install boots to Ubuntu desktop when run from within a virtual machine under VMWare Player 16.

[Chris Guiver (guiverc)]

Thank you for taking the time to report this issue and helping to make Ubuntu better.

This package failure looks like it was caused by bad ISO download, corrupted install media, or device failure, assuming /dev/sdb is your installation media; the error "/dev/sdb: No medium found" is an ability to recognize the media as valid. The question to attempt to download is the solution offered in that circumstance.

Possibly useful : https://tutorials.ubuntu.com/tutorial/tutorial-how-to-verify-ubuntu#0 though it sounds like that was not your issue (having performed checks), but the writing of the ISO was not done correctly (possibly with older software that couldn't cope with 20.04.3 media).

For Support, this bug report can be converted into a question, or you can ask a question on https://answers.launchpad.net/ubuntu. You can also find help with your problem in the support forum of your local Ubuntu community http://loco.ubuntu.com/ or asking at https://askubuntu.com or https://ubuntuforums.org, or for more support options please look at https://discourse.ubuntu.com/t/community-support/709

[Scott (scottmeup)]

Thanks for your reply Chris,

The software used to create the media was rufus 3.17, following this tutorial: https://ubuntu.com/tutorials/create-a-usb-stick-on-windows

The media boots without error from within a virtual machine via plopboot and plopkexec, but not on bare metal of the same hardware, and successfully boots on a Lenovo Thinkcentre M700.
I'm not sure why the media is failing to complete booting only on bare metal for the Macbook.

If there are any other validation steps I can take I would be glad to do so.

The issue has been posted on ask ubuntu and the suggestions so far have been to validate the media: https://askubuntu.com/questions/1383225/how-to-boot-from-a-live-usb-stick-on-a-mac

I look forward to hearing from you.
Kind regards, Scott.

[Chris Guiver (guiverc)]

You mention the media working on the virtual machine; was the virtual machine reading the image on the thumb-drive? or just using the ISO on disk or other media?

(if it was reading the ISO on different media; be it disk drive, network share it doesn't discount my blaming media; if however you'd setup the VM to boot from the same USB media - that is different I believe).