renai42

Q: Mid-2015 iMac won't reboot into Windows 10 install

hi folks,

 

I have a brand new, mid-2015 Retina 27" iMac.

 

I'm trying to install Windows 10 (or, really, any version of Windows) on it via Bootcamp in a dual-boot scenario, so that I can do some gaming via Steam.

 

I have downloaded the latest Windows 10 iso from Microsoft.

 

Bootcamp Assistant partitions the drive, but when it reboots, it does not go into the Windows 10 installer. Instead, there is a delayed booting period, and then it dumps me back into Mac OS X. Holding down option does not show a Windows 10 bootable option. However, the drive has been partitioned -- the Windows partition shows up on the desktop in Mac OS X and in Disk Utility.

 

I know that Microsoft recently updated the Windows 10 isos, and I suspect what is happening here is that Bootcamp Assistant has not yet caught up.

 

I also suspect this problem is quite widespread.

 

Can anyone let me know what I should do? I also have a Windows 7 disk, but Bootcamp Assistant tells me I need Windows 8 minimum ... and Microsoft no longer sells copies of Windows 8.

 

Kind regards,

 

Renai

iMac, Windows 10

Posted on Dec 30, 2015 6:21 AM

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Q: Mid-2015 iMac won't reboot into Windows 10 install

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  • by dialabrain,

    dialabrain dialabrain Dec 30, 2015 6:41 AM in response to renai42
    Level 5 (6,386 points)
    Mac App Store
    Dec 30, 2015 6:41 AM in response to renai42
  • by renai42,

    renai42 renai42 Dec 30, 2015 7:00 AM in response to dialabrain
    Level 1 (0 points)
    Dec 30, 2015 7:00 AM in response to dialabrain

    Yes, I followed those instructions precisely and got the result I detailed above.

  • by austinmiles,

    austinmiles austinmiles Dec 30, 2015 9:50 AM in response to renai42
    Level 1 (0 points)
    Dec 30, 2015 9:50 AM in response to renai42

    I am having this exact same issue

     

    I went back into OSX and copied the ISO files into the BOOTCAMP drive and it did load, but it couldn't find any of the drivers that were supposedly downloaded by the bootcamp assistant, so I backed out and undid that.

  • by Loner T,

    Loner T Loner T Dec 30, 2015 10:03 AM in response to renai42
    Level 7 (24,307 points)
    Safari
    Dec 30, 2015 10:03 AM in response to renai42

    Please post the md5sum of the ISO you are using.

  • by austinmiles,

    austinmiles austinmiles Dec 30, 2015 10:50 AM in response to renai42
    Level 1 (0 points)
    Dec 30, 2015 10:50 AM in response to renai42

    I solved this for myself and here's how.

     

    I went back into boot camp assistant. And had it remove the partition and go back to normal. I tried to just restart the boot camp process again but it was telling me the ISO wasnt valid so I restarted the machine. Back at square one.

     

    after restarting the machine go back into boot camp and repartition and reselect the ISO. wait for it to download support files again and sit by it when it restarts.

     

    as soon as the screen goes black hold the option key. Then you will get the option to boot from OS X or Windows. choose Windows and it should work fine.

     

    When it asks what disk to install on say bootcamp and hit reformat. It will format it as NTFS and continue from there.

     

    I hope that helps. (Sorry for weird typos. I am on my phone as my computer is getting setup for Windows now)

  • by dialabrain,

    dialabrain dialabrain Dec 30, 2015 11:35 AM in response to renai42
    Level 5 (6,386 points)
    Mac App Store
    Dec 30, 2015 11:35 AM in response to renai42

    It seems not everyone was following all the directions.

    How to install Windows using Boot Camp - Apple Support

  • by austinmiles,

    austinmiles austinmiles Dec 30, 2015 11:43 AM in response to dialabrain
    Level 1 (0 points)
    Dec 30, 2015 11:43 AM in response to dialabrain

    There is nothing in those instructions that say anything about holding option or else having to restart the whole process. nothing about how you will have to undo the partitioning. Nothing about restarting the machine because it will read your ISO as corrupt. The latter part is in the instructions which I was just reiterating.

  • by dialabrain,

    dialabrain dialabrain Dec 30, 2015 11:45 AM in response to austinmiles
    Level 5 (6,386 points)
    Mac App Store
    Dec 30, 2015 11:45 AM in response to austinmiles

    True. Probably because you don't actually have to do that. At least I didn't.

  • by austinmiles,

    austinmiles austinmiles Dec 30, 2015 11:59 AM in response to dialabrain
    Level 1 (0 points)
    Dec 30, 2015 11:59 AM in response to dialabrain

    Are you coming to support discussions simply to tell people that the issues they are experiencing aren't actually happening because it didn't happen that way for you? Those instructions aren't even entirely relevant to the mid 2015 models.

  • by dialabrain,

    dialabrain dialabrain Dec 30, 2015 3:50 PM in response to austinmiles
    Level 5 (6,386 points)
    Mac App Store
    Dec 30, 2015 3:50 PM in response to austinmiles

    I see. I guess the problem was I was installing Windows 10 on an Early 2015 MacBook Retina and a Late 2015 iMac 5k running 10.11.3 Beta (15D9c) on one and 10.11.2 on the other. Sorry.

     

    Sounds like Mid 2015 was a bad time for Bootcamp.

  • by renai42,

    renai42 renai42 Dec 30, 2015 11:30 PM in response to Loner T
    Level 1 (0 points)
    Dec 30, 2015 11:30 PM in response to Loner T

    "Please post the md5sum of the ISO you are using."


    MD5 (Win10_1511_English_x64.iso) = a0d4271b7537732a060909fd39d54829

  • by Loner T,

    Loner T Loner T Dec 31, 2015 8:04 AM in response to renai42
    Level 7 (24,307 points)
    Safari
    Dec 31, 2015 8:04 AM in response to renai42

    It matches the copy I downloaded.

    openssl md5 Win10_1511_English_x64.iso

    MD5(Win10_1511_English_x64.iso)= a0d4271b7537732a060909fd39d54829

     

    BCA can and does fail at several places, especially in El Capitan. The typical places are

     

    1. During Partitioning.

    2. During Windows Software Download.

    3. After Partitioning before handing control to EFI Booter (on 2015 Macs).

    4. Fusion drives and BCA 6.0 seem to be at significant odds on how to partition disks.

    5. If any external storage is attached, Windows Installer creates its own EFI substructures on disk, which result from the bad assumption that it is being installed on a PC and there is no other OS on the machine.

    6. External booting media is incapable of boot support, if used (2012-2014 Macs).

    7. Optical drive is broken (2012 or earlier Macs).

  • by dialabrain,

    dialabrain dialabrain Dec 31, 2015 8:47 AM in response to renai42
    Level 5 (6,386 points)
    Mac App Store
    Dec 31, 2015 8:47 AM in response to renai42

    FWIW, For me it was easiest to create the Windows bootable USB Key from the .iso, boot that and install Windows 10 from there.

  • by renai42,

    renai42 renai42 Dec 31, 2015 5:08 PM in response to Loner T
    Level 1 (0 points)
    Dec 31, 2015 5:08 PM in response to Loner T

    "BCA can and does fail at several places, especially in El Capitan. The typical places are

     

    1. During Partitioning.

    2. During Windows Software Download.

    3. After Partitioning before handing control to EFI Booter (on 2015 Macs).

    4. Fusion drives and BCA 6.0 seem to be at significant odds on how to partition disks.

    5. If any external storage is attached, Windows Installer creates its own EFI substructures on disk, which result from the bad assumption that it is being installed on a PC and there is no other OS on the machine.

    6. External booting media is incapable of boot support, if used (2012-2014 Macs).

    7. Optical drive is broken (2012 or earlier Macs)."

     

    So would you recommend just trying again? And seeing if it will install a second time around?

     

    Alternatively, what is the process involved in installing from USB? I have plenty of OS install experience (Linux etc), but not sure whether, if I just plain boot from a Win10 install USB and then install Win10 on a new partition created by Bootcamp, whether the Apple bootloader will then work properly when I reboot -- will Win10 overwrite Apple's bootloader? Or will Apple's bootloader recognise the new Win10 partition?

     

    Cheers for any help!

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