MODSIGN: Couldn't get UEFI db list Couldn't get size: 0x800000000000000e

Problem on a Mac Mini Mid 2011. I have looked through other articles and couldn't get help. Any help?

Add the grub arguments noapic noacpi nosplash in place of quiet splash. noapic and noacpi are kernel boot options. ACPI stands for Advanced Configuration and Power Interface and APIC stands for Advanced Programmable Interrupt Controller.

Immediately after the BIOS/UEFI splash screen during boot, with BIOS, quickly press and hold the Shift key, which will bring up a GNU GRUB menu screen. With UEFI press (perhaps several times) the Esc key to get to the GNU GRUB menu screen. Sometimes the manufacturer's splash screen is a part of the Windows bootloader, so when you power up the machine it goes straight to the GNU GRUB menu screen, and then pressing Shift is unnecessary.

You will see a GNU GRUB menu screen that looks like this:

Press e to enter editing mode. This will bring up a GNU GRUB screen that looks like this:

Use the arrow keys to navigate when screen editing the above screen. Navigate to after the string on this screen that starts with root=. In this example screen the full string is root= followed by UUID= and a hexadecimal string as shown below:

root=UUID=bcf15ef2-a0b2-4753-9558-8399dd12a729   

Immediately after this string replace quiet splash by noapic noacpi nosplash. This change is only temporary — it will just be used once and GRUB won't remember it in the future. It may be possible to make these changes permanent by changing the ACPI and APIC settings in the Mac Mini's UEFI firmware. Press Ctrl+X or F10 to boot with the kernel boot options that were added. If you make a mistake, press Esc to go back to the previous screen.

Use a live usb of the same ubuntu version.
Open terminal.

sudo -i
fsck /dev/sdaX

Replace 'X' with your root disk name,and then with all other drives present.
You can check it with "fdisk -l".
Reboot.Remove live usb.
Ta-da, its done.