Cannot install Ubuntu 17.10 on MBP 9,2 (boot problems)

Question

My problem is a bit hard to formulate, therefore the vague title. Basically, I can't get Ubuntu to boot from my Macbook Pro, but I'm completely unsure where this problem comes from.

To give a little bit of backstory: I had macOS and Arch dual-booting on my machine for a year or so now and after an update, Arch stopped working (vmlinuz-linux timed out). Tried looking into the drive from macOS, but macOS didn't start too (displayed a prohibitory sign on startup). I felt that fixing this issue would take a loong time and I'd be better off just installing Ubuntu for now. Huh.

So I installed Ubuntu 17.10 via a USB stick, following Canonical tutorials like this one. Needless to say, my computer did not boot, showing a flashing folder with a question mark instead (after showing a white screen for about 30 seconds - normally it only needs about 10 seconds to boot). People say this means that the computer does not know where to boot from. I looked into the interwebs and found different suggestions:

1. Boot in BIOS/legacy mode (1st try): To do this, I created a new msdos partition table with gparted (in Ubuntu Live from USB) for my SSD, created a 1MiB FAT32 partition, enabled the boot flag for it and rebooted (based on a comment found here). Another install of Ubuntu changed the partition table back to GPT, however, and added a EFI partition. Also, it still didn't boot.
2. Boot in BIOS/legacy mode (2nd try): I burned a DVD with Ubuntu on it, then booted into the boot menu (not sure if this is how it's called, I held down the Alt key during startup) and on the first try, I saw three alternatives:
   1. EFI boot (with a harddrive icon): does not always show up (pattern seems to be that it only shows up after resetting the NVRAM when I didn't use it before), but when it does and I choose it, error: file '/boot/' not found appears.
   2. Windows (with a CD icon): when I choose this, I hear the DVD spinning faster, the display might change in brightness and turn black (or not) and a blinking underline-type cursor might appear (or not), but then the DVD stops spinning and nothing happens.
   3. EFI boot (with a CD icon): same as the first option, this shows me error: file '/boot/' not found.
3. Install Debian: Did this, seemed like it installed itself in BIOS/legacy mode, as Disk Utility in recovery mode showed that the file system is 'Master Boot Record' and Ubuntu warned me upon installation that there is an OS in BIOS/legacy mode installed already. Upon startup, the flashing folder icon appears and when I boot with the Alt key held down, then urgh... last time the error message error: file '/boot/' not found appeared, now the flashing folder icon.
4. Start recovery mode and select 'Startup Disk' / reinstall macOS: Booted into recovery mode through the Internet, but neither the 'Startup Disk'-program nor the macOS installer found my hard drive. Note, however, that Ubuntu has no problem to find my hard drive when it is booted in Live mode. I also ran the 'Disk Utility' program, but it could not repair the disk and frequently stops showing the disk in the left panel.

Do you know anything I could do to fix this?

Also, just to add confusion: The computer did successfully boot into Debian and Ubuntu once and then never again. Couldn't reproduce anything (what I tried was resetting the NVRAM and entering recovery mode to select my hard drive as start disk).

I went to a apple store and they told me that the thing they‘d try is replacing the SSD cable. Can a broken SSD cable cause such weird problems? By the way, I ran badblocks from Ubuntu and it found no problems.

Answer 1

Below is the sequence of steps needed install Ubuntu on your Mac.

1. Install Ubuntu for EFI booting. You should boot the installer from a USB flash drive.
2. After you are finished installing Ubuntu, you will not be able to boot Ubuntu from your internal drive. The remaining steps correct this problem.
3. Boot to Ubuntu Live.
4. From the Desktop, press the control+option+T keys to open a Terminal window.

5. Enter the command shown below.

   sudo  fdisk  -l  /dev/sda
   

   Below is the output I saw from entering this command. (This image is from a Ubuntu Desktop 16.04.3 Live boot)

   Note: For a better view, click on the image or open the image in a new window.

   

6. From the output of the sudo fdisk -l /dev/sda command, determine the device for the EFI System partition. For me, this was /dev/sda1. If you determine a different device, make the appropriate substitutions.

7. Enter the commands given below to make Ubuntu appear in the Startup Manager.

   sudo  bash
   mkdir  efi
   mount  /dev/sda1  efi
   cd  efi/EFI
   mkdir  BOOT
   cp  ubuntu/grubx64.efi  BOOT/bootx64.efi
   cd  ~
   umount  efi
   rmdir  efi
   exit
   exit
   

8. Shutdown Ubuntu live.

9. Startup the Mac and immediately hold down the option key until the Startup Manager icons appear.

10. Click on the hard disk icon labeled "EFI Boot". Next, while holding down the control key, click on the circular arrow below this icon.

You are finished. Your Mac will now automatically boot to Ubuntu on startup and restart.