This bug is now two years old but I stumbled just recently over it. I'd like to add my story about that bug of the missing "mmx64.efi" file.
I am running a custom built PC based on an ASUS Z97-A/USB 3.1 mainboard. Shortly after the COVID-19 era started (earlier this year), I made a fresh dual boot installation consisting of Windows 10 Pro and Linux Mint 20 (which is based on Ubuntu 20.04). Since then my dual boot system is working just fine with Secure Boot enabled. Anyhow, now and then I like to try new GNU/Linux distros booting from an USB SD Card reader/writer (e.g. different Linux Mint and/or Ubuntu flavors). The writing to the boot device happens with dd and the few mentioned distros did boot live from an USB media about a month ago, indeed. But now for a week or so my system cannot boot these USB live GNU/Linux distros anymore. The error message on the display says: --------------------------------------------------- ERROR Verification failed: (0x1A) Security Violation Failed to load image: Security Policy Violation Failed to open \EFI\BOOT\mmx64.efi - Not Found Failed to load image \EFI\BOOT\mmx64.efi: Not Found start_image() returned Not Found --------------------------------------------------- I just don't know what might have happend in the meanwhile. But still my dual boot system is working fine. The workaround about copying or renaming the missing mmx64.efi file on the USB live boot media does not work for me. And the comment #55 prevented me from messing around with efivars as I don't want to break my system as long itself is working fine. It's just the USB live distros that don't boot. The next curious fact is that I own another single boot Laptop (Acer TravelMate B115-M) with Secure Boot enabled and also Linux Mint 20 installed. The installed operating system is working just fine but again no USB live distro is booting. It's the same error (file mmx64.efi not found). My only attempt trying to solve this bug so far is this: The UEFI/BIOS of both my machines offer to restore all Secure Boot related stuff (e.g. like clearing trusted keys and such). After I made this I successfully could boot of an USB live distro *once*. Upon reboot and starting up the installed Linux Mint 20 system I was not able to repeat to boot an USB live distro anymore. However, still my installed Linux Mint 20 system is working fine. So technically, I would have to clear Secure boot settings in the UEFI/BIOS every time I want to boot an USB live distro? But this is not a convenient solution at all. In my observations the only connection between my both computers is the installed Linux Mint 20 operating system. Hope that gives someone a clue? -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1798171 Title: System fails to boot with \EFI\BOOT\mmx64.efi - Not Found To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/debian-installer/+bug/1798171/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
