My computer is only booting windows.

My most recent attempt to use boot-repair has this result. I have disabled secure boot in the bios.

I have attempted to set the boot flags using gparted as specified here. It's not clear to me whether sdb5, the linux partition, should have the boot flag enabled; I've tried boot-repair both ways. I have the boot flag turned on for the EFI partition, sdb1. I have two issues that come up on gparted:

It is unable to detect the file system on the windows partition, sdb2, as seen here: enter image description here

And I'm getting the error "The driver descriptor says the physical block size is 2048 bytes, but Linux says it is 512 bytes." I think this is referring to the USB stick that I'm booting from; it's not clear to me whether this affects any attempts to use gparted on the hard drive.

  • 1
    Did you create your USB Boot from the usb-creator-gtk in Ubuntu? If so, it formats the USB to the 2048 causing the error to appear. – Terrance Jul 19 '17 at 21:50
  • @Terrance I think so. I used whatever tool ubuntu came with. – Dustan Levenstein Jul 19 '17 at 21:56
  • @Terrance Is it a problem for what I'm trying to do now? – Dustan Levenstein Jul 19 '17 at 21:57
  • It might be. Try looking into mkusb to create the bootable usb. It should format it correctly. Or, if you can, try burning a DVD of the ISO just for installation purposes that you can use for reinstalling Grub. I kind of lost faith in the usb-creator-gtk when they removed the persistence from it and other things. See askubuntu.com/a/772100/231142 – Terrance Jul 19 '17 at 22:03
  • 2
    With UEFI, the boot flag should only ever be on the ESP - efi system partition. The error on blocksize is usually on the flash drive, and can be ignored. Do not reboot with flash drive plugged in, unmount before rebooting & remove it. Your system promotes flash drive to sda, which can confuse things. What brand & model system. Last report from efibootmgr shows lots of entries, but one is now ubuntu, does that boot from UEFI boot menu. Note sdb2 is system reserved for Windows & is unformatted as required by Windows. But gparted shows error on unformatted partitions, so ignore that error. – oldfred Jul 19 '17 at 22:36

The comments, especially from oldfred, have covered the fact that most of the "problems" you've identified in your question are not really problems. What we're left with, then, is what's in the first line of the question:

My computer is only booting windows.

This is a bit vague, but I suspect you mean it's booting straight to Windows. The reason is likely this, from your Boot Repair summary:

=================== efibootmgr -v
BootCurrent: 0001
Timeout: 0 seconds
BootOrder: 000C,0001,2001,2002,2003
Boot0001* Linux HD(1,MBR,0x61,0x3860,0x1300)/File(EFIBootgrubx64.efi)RC
Boot0007* ubuntu    HD(1,GPT,412f327c-c30a-4893-81c5-ad5ded944d84,0x800,0x32000)/File(EFIubuntushimx64.efi)
Boot000C* Windows Boot Manager  HD(1,GPT,412f327c-c30a-4893-81c5-ad5ded944d84,0x800,0x32000)/File(EFIMicrosoftBootbootmgfw.efi)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.e.a.8.6.2.c.-.5.c.d.d.-.4.e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.}....................

(I've removed some irrelevant lines for clarity.) The BootOrder line specifies the order in which various boot loaders will be run. In your case, Boot000C, which is Windows Boot Manager, is run first. This is a common problem with two or three common causes. I recommend you read the following questions and their answers:

These problems aren't identical to yours, but the solutions are pretty similar. In particular, using EasyUEFI or bcdedit in Windows is likely to fix the problem. Note that the last link is to a problem that's pretty dire, and increasingly uncommon. Go there only if other solutions don't work for you. (The fact that you've got an ubuntu entry in the efibootmgr output and a BootOrder line makes me think that it won't come to that for you, but I could be wrong about that.)

  • 1
    Bingo! bcdedit did the trick. Thanks so much!!! :) – Dustan Levenstein Jul 20 '17 at 3:01

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