Attempting to install High Sierra alongside Windows 10 (1809 October 2018 ISO): "This disk cannot be used to startup your computer"

Question

I have installed Windows 10 (in UEFI mode - no bios emulation) first on an empty SSD of an iMac (mid-2011). Once I was done I attempted to perform a usb-install of High Sierra (I have a created an HFS+ partition around 180GB or so at the end of the SSD). However the MacOS X installer for High Sierra complains that the disk in question cannot be a startup disk. Partitioning info looks like so:

-bash-3.2# diskutil list disk0

/dev/disk0 (internal, physical):

   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *512.1 GB   disk0
   1:           Windows Recovery                         523.2 MB   disk0s1
   2:                        EFI NO NAME                 104.9 MB   disk0s2
   3:         Microsoft Reserved                         16.8 MB    disk0s3
   4:       Microsoft Basic Data BOOTCAMP                322.1 GB   disk0s4
   5:                  Apple_HFS Windows Shell EFI       67.1 MB    disk0s5
   6:                  Apple_HFS MacOS                   188.2 GB   disk0s6

-bash-3.2# gpt -r show disk0
       start        size  index  contents
           0           1         PMBR
           1           1         Pri GPT header
           2          32         Pri GPT table
          34        2014         
        2048     1021952      1  GPT part - DE94BBA4-06D1-4D40-A16A-BFD50179D6AC
     1024000      204800      2  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
     1228800       32768      3  GPT part - E3C9E316-0B5C-4DB8-817D-F92DF00215AE
     1261568   629114880      4  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
   630376448      131072      5  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
   630507520   367659663      6  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
   998167183     2048000         
  1000215183          32         Sec GPT table
  1000215215           1         Sec GPT header

The only thing I can imagine being wrong is that the EFI partition is either too small or is not being first on the disk. If that's the case is there a way to salvage the situation without reformatting everything?

@DavidAnderson Thanks for tuning in. I installed Windows10. As far as the "Windows Shell EFI" is concerned it's a partition I made by hand in order to place inside it Intel's Shell.efi along with a script employing it in order to boot Windows10 from the MacOS bootloader (the one that pops up when you press the 'Alt' key during boot): reddit.com/r/mac/comments/2fy3be/… — XDS, Commented Dec 27, 2018 at 14:40
Which version of Windows 10. For example, the last two releases were 1803 (April 2018) and 1809 (October 2018). The winver command will show the version in a popup. I am surprised Windows did not appear in the Mac Startup Manager. I did not have this problem when I installed an EFI booting Windows 10 to an USB external drive. I also have a iMac (21.5 inch, Mid 2011) with High Sierra installed. — David Anderson, Commented Dec 27, 2018 at 15:34
@DavidAnderson oh Windows10 1809 October 2018 ISO which the latest and greatest at the time of this writing. Windows 10 EFI option did appear on the manager but I've always hesitated to use it (taking the hint from the guide I linked above). I guess it's safe to use it afterall. Thanks for the insight on this side-issue. — XDS, Commented Dec 27, 2018 at 15:40

David Anderson · Accepted Answer · 2018-12-29 18:23:53Z

Your disk0s1 has nothing in it. What was suppose to go into this partition ended up in disk0s4. You can blame Microsoft for this. The Windows installer just did not make the partition larger enough. So there is two ways to look at this.

You screwed up an might as well just start over. Personally, I would recommend sticking with a BIOS boot. For your model Mac, the Windows Support software from Apple working best with this type of booting. If you insist on an EFI boot, then I suggest you follow the guidelines for partitioning outlined in the Microsoft document: UEFI/GPT-based hard drive partitions. I would recommend at least 800 MB for the WRE partition. You can get more information about the WRE by reading Windows Recovery Environment (Windows RE).
You could shrink disk0s1 and create a new larger disk0s2, then try to install High Sierra. I would make the EFI partition at least 209,715,200 bytes in size. If this does not work, then change disk0s1 to a EFI partition and try installing High Sierra again.

I can kind of outline some of the steps, but you first would have to decide what you what to do.

Steps to merge `disk0s1` and `disk0s2` into a single EFI partition.

You can either boot from the Windows USB installer or from the WinRE on you internal drive. In the steps below, the WinRE was used.

Hold down the shift key when selecting Restart. This should boot the Mac to the WinRE.
Get to a Command Prompt window by selecting Troubleshoot -> Advanced options -> Command Prompt.
Enter the following commands. The last command lists the drive letters assigned to the volumes. In my case, the Windows volume was assigned the letter C. If your Windows volume is assigned a different letter, then make the appropriate letter substitution in the rest of the steps.
```
diskpart
sel disk 0
sel part 2
assign letter=s
list vol
```
Copy the contents of the EFI volume to the Windows volume.
```
exit
md c:\drive_s
xcopy s:\ c:\drive_s /e /h
```

Remove the existing EFI partition.

diskpart
sel disk 0
sel part 2
del part override

Change the existing empty WinRE volume to an EFI volume. The help commands were entered so selected output could be copy and pasted to aid in entering the subsequent gpt and set id commands.

Note: The partition type needed to be set to Basic data partition before entering the extend command. Afterwards, the partition type is set to EFI System partition.
```
sel part 1
help gpt
GPT ATTRIBUTES=0x0000000000000000
help setid
SET ID=ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
extend
set id=c12a7328-f81f-11d2-ba4b-00a0c93ec93b
format fs=fat32 label=EFI quick
```

Copy the saved files to the new EFI volume.

assign letter=s
exit
xcopy c:\drive_s\* s:\ /e /h

Remove the files from the Windows volume and close the Command Prompt window.
```
rd /s /q c:\drive_s
exit
```
Select Continue.

Note: I did not need to rebuild the BCD. If your computer does not boot properly, then the BCD probably will need to be rebuilt.

Below is the output when I entered the above commands. Windows 10 (1809) was installed in VirtualBox and was running in Audit mode.

Microsoft Windows [Version 10.0.17763.107]
(c) 2018 Microsoft Corporation. All rights reserved.

X:\windows\system32>diskpart

Microsoft DiskPart version 10.0.17763.1

Copyright (C) Microsoft Corporation.
On computer: MININT-GA4EHL6

DISKPART> sel disk 0

Disk 0 is now the selected disk.

DISKPART> sel part 2

Partition 2 is now the selected partition.

DISKPART> assign letter=s

DiskPart successfully assigned the drive letter or mount point.

DISKPART> list vol

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 0     D                       CD-ROM          0 B  No Media
  Volume 1         Recovery     NTFS   Partition    499 MB  Healthy
  Volume 2     C                NTFS   Partition    105 GB  Healthy
* Volume 3     S                FAT32  Partition     99 MB  Healthy    Hidden

DISKPART> exit

Leaving DiskPart...

X:\windows\system32>md c:\drive_s

X:\windows\system32>xcopy s:\ c:\drive_s /e /h
S:\EFI\Microsoft\Boot\BCD
S:\EFI\Microsoft\Boot\BCD.LOG
S:\EFI\Microsoft\Boot\boot.stl
S:\EFI\Microsoft\Boot\bootmgfw.efi
S:\EFI\Microsoft\Boot\bootmgr.efi
S:\EFI\Microsoft\Boot\memtest.efi
S:\EFI\Microsoft\Boot\winsipolicy.p7b
S:\EFI\Microsoft\Boot\BOOTSTAT.DAT
S:\EFI\Microsoft\Boot\kd_02_10df.dll
S:\EFI\Microsoft\Boot\kd_02_10ec.dll
S:\EFI\Microsoft\Boot\kd_02_1137.dll
S:\EFI\Microsoft\Boot\kd_02_14e4.dll
S:\EFI\Microsoft\Boot\kd_02_15b3.dll
S:\EFI\Microsoft\Boot\kd_02_1969.dll
S:\EFI\Microsoft\Boot\kd_02_19a2.dll
S:\EFI\Microsoft\Boot\kd_02_1af4.dll
S:\EFI\Microsoft\Boot\kd_02_8086.dll
S:\EFI\Microsoft\Boot\kd_07_1415.dll
S:\EFI\Microsoft\Boot\kd_0C_8086.dll
S:\EFI\Microsoft\Boot\kdstub.dll
S:\EFI\Microsoft\Boot\BCD.LOG1
S:\EFI\Microsoft\Boot\BCD.LOG2
S:\EFI\Microsoft\Boot\bg-BG\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\bg-BG\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\cs-CZ\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\cs-CZ\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\cs-CZ\memtest.efi.mui
S:\EFI\Microsoft\Boot\da-DK\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\da-DK\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\da-DK\memtest.efi.mui
S:\EFI\Microsoft\Boot\de-DE\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\de-DE\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\de-DE\memtest.efi.mui
S:\EFI\Microsoft\Boot\el-GR\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\el-GR\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\el-GR\memtest.efi.mui
S:\EFI\Microsoft\Boot\en-GB\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\en-GB\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\en-US\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\en-US\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\en-US\memtest.efi.mui
S:\EFI\Microsoft\Boot\es-ES\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\es-ES\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\es-ES\memtest.efi.mui
S:\EFI\Microsoft\Boot\es-MX\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\es-MX\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\et-EE\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\et-EE\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\fi-FI\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\fi-FI\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\fi-FI\memtest.efi.mui
S:\EFI\Microsoft\Boot\fr-CA\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\fr-CA\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\fr-FR\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\fr-FR\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\fr-FR\memtest.efi.mui
S:\EFI\Microsoft\Boot\hr-HR\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\hr-HR\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\hu-HU\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\hu-HU\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\hu-HU\memtest.efi.mui
S:\EFI\Microsoft\Boot\it-IT\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\it-IT\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\it-IT\memtest.efi.mui
S:\EFI\Microsoft\Boot\ja-JP\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\ja-JP\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\ja-JP\memtest.efi.mui
S:\EFI\Microsoft\Boot\ko-KR\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\ko-KR\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\ko-KR\memtest.efi.mui
S:\EFI\Microsoft\Boot\lt-LT\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\lt-LT\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\lv-LV\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\lv-LV\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\nb-NO\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\nb-NO\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\nb-NO\memtest.efi.mui
S:\EFI\Microsoft\Boot\nl-NL\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\nl-NL\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\nl-NL\memtest.efi.mui
S:\EFI\Microsoft\Boot\pl-PL\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\pl-PL\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\pl-PL\memtest.efi.mui
S:\EFI\Microsoft\Boot\pt-BR\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\pt-BR\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\pt-BR\memtest.efi.mui
S:\EFI\Microsoft\Boot\pt-PT\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\pt-PT\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\pt-PT\memtest.efi.mui
S:\EFI\Microsoft\Boot\qps-ploc\memtest.efi.mui
S:\EFI\Microsoft\Boot\ro-RO\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\ro-RO\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\ru-RU\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\ru-RU\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\ru-RU\memtest.efi.mui
S:\EFI\Microsoft\Boot\sk-SK\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\sk-SK\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\sl-SI\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\sl-SI\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\sr-Latn-RS\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\sr-Latn-RS\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\sv-SE\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\sv-SE\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\sv-SE\memtest.efi.mui
S:\EFI\Microsoft\Boot\tr-TR\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\tr-TR\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\tr-TR\memtest.efi.mui
S:\EFI\Microsoft\Boot\uk-UA\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\uk-UA\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\zh-CN\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\zh-CN\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\zh-CN\memtest.efi.mui
S:\EFI\Microsoft\Boot\zh-TW\bootmgfw.efi.mui
S:\EFI\Microsoft\Boot\zh-TW\bootmgr.efi.mui
S:\EFI\Microsoft\Boot\zh-TW\memtest.efi.mui
S:\EFI\Microsoft\Boot\Fonts\chs_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\cht_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\jpn_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\kor_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\malgunn_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\malgun_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\meiryon_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\meiryo_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\msjhn_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\msjh_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\msyhn_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\msyh_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\segmono_boot.ttf
S:\EFI\Microsoft\Boot\Fonts\segoen_slboot.ttf
S:\EFI\Microsoft\Boot\Fonts\segoe_slboot.ttf
S:\EFI\Microsoft\Boot\Fonts\wgl4_boot.ttf
S:\EFI\Microsoft\Boot\Resources\bootres.dll
S:\EFI\Microsoft\Boot\Resources\en-US\bootres.dll.mui
S:\EFI\Microsoft\Recovery\BCD
S:\EFI\Microsoft\Recovery\BCD.LOG
S:\EFI\Microsoft\Recovery\BCD.LOG1
S:\EFI\Microsoft\Recovery\BCD.LOG2
S:\EFI\Boot\bootx64.efi
138 File(s) copied

X:\windows\system32>diskpart

Microsoft DiskPart version 10.0.17763.1

Copyright (C) Microsoft Corporation.
On computer: MININT-GA4EHL6

DISKPART> sel disk 0

Disk 0 is now the selected disk.

DISKPART> sel part 2

Partition 2 is now the selected partition.

DISKPART> del part override

DiskPart successfully deleted the selected partition.

DISKPART> sel part 1

Partition 1 is now the selected partition.

DISKPART> help gpt

    On basic GUID partition table (GPT) disks, assigns the GPT attribute(s) to
    the partition with focus.

Syntax:  GPT ATTRIBUTES=<N>

    ATTRIBUTES=<N>

                The hexadecimal value indicating the attributes to apply to the
                partition with focus. The GPT attribute field is a 64-bit field
                that contains two subfields. The higher field is interpreted
                only in the context of a particular partition type GUID, while
                the lower field is common to all partition types.

                The following attribute can be set on any partition:

                0x0000000000000001 marks the partition as required. This
                indicates to all disk management utilities that the partition
                should not be deleted. The EFI System partition contains only
                those binaries necessary to start the operating system. This
                makes it easy for original equipment manufacturer (OEM) or
                operating system-specific binaries to be placed in other
                partitions.

                For basic data partitions, the following attributes are defined:

                0x8000000000000000
                GPT_BASIC_DATA_ATTRIBUTE_NO_DRIVE_LETTER
                Prevents the partition from having a drive
                letter automatically assigned. By default, each partition is
                assigned a new drive letter and a volume GUID pathname. Both
                the drive letter and the volume GUID pathname can be used to
                open the volume using Win32 APIs. Setting this attribute ensures
                that when a disk is moved to a new computer, a new drive letter
                will not be automatically generated. Instead, the user can
                manually assign drive letters.

                0x4000000000000000
                GPT_BASIC_DATA_ATTRIBUTE_HIDDEN
                Defines the partition's volume as hidden.
                Setting this attribute specifies that the volume will not be
                assigned a drive letter or a volume GUID pathname. Both
                the drive letter and the volume GUID pathname can be used to
                open the volume using Win32 APIs. A hidden partition's
                volume is not reported by Win32 APIs such as FindFirstVolume
                and FindNextVolume.

                0x2000000000000000
                GPT_BASIC_DATA_ATTRIBUTE_SHADOW_COPY
                Defines the partition as being a Volume Snapshot Service
                shadow copy volume. Fle system filters use this flag to
                prevent the filter from attaching to the volume.

                0x1000000000000000
                GPT_BASIC_DATA_ATTRIBUTE_READ_ONLY
                Prevents the volume from being written to.

                Other attributes may be added by Microsoft at any time.

    GPT partition attributes give additional information about the use of the
    partition.

    A basic GPT partition must be selected for this operation to succeed.

    Caution:

        Changing the GPT attributes might cause your basic data volumes to
        fail to be assigned drive letters, or prevent the file system from
        mounting. Unless you are an original equipment manufacturer (OEM)
        or an IT professional experienced with GPT disks, do not change GPT
        attributes.

Example:

    GPT ATTRIBUTES=0x8000000000000000
    GPT ATTRIBUTES=0xF000000000000001

DISKPART> GPT ATTRIBUTES=0x0000000000000000

DiskPart successfully assigned the attributes to the selected GPT partition.

DISKPART> help setid

    Changes the partition type field for the partition with focus.

Syntax:  SET ID={<BYTE> | <GUID>} [OVERRIDE] [NOERR]

    ID={<BYTE> | <GUID>}

                Specifies the new partition type.

                For master boot record (MBR) disks, you can specify a partition
                type byte, in hexadecimal form, for the partition. Any
                partition type byte can be specified with this parameter except
                for type 0x42 (LDM partition). Note that the leading '0x' is
                omitted when specifying the hexadecimal partition type.

                For GUID partition table (GPT) disks you can specify a
                partition type GUID for the partition. Recognized GUIDs
                include:

                    EFI System partition:
                        c12a7328-f81f-11d2-ba4b-00a0c93ec93b

                    Basic data partition:
                        ebd0a0a2-b9e5-4433-87c0-68b6b72699c7

                Any partition type GUID can be specified with this parameter
                except for the following:

                    Microsoft Reserved partition:
                        e3c9e316-0b5c-4db8-817d-f92df00215ae

                    LDM Metadata partition on a dynamic disk:
                        5808c8aa-7e8f-42e0-85d2-e1e90434cfb3

                    LDM Data partition on a dynamic disk:
                        af9b60a0-1431-4f62-bc68-3311714a69ad

                    Cluster Metadata partition:
                        db97dba9-0840-4bae-97f0-ffb9a327c7e1


                Other than the limitations mentioned, DiskPart otherwise does
                not check the partition type for validity except to ensure that
                it is a byte in hexadecimal form or a GUID.

    OVERRIDE    Enables DiskPart to force the file system on the volume to
                dismount before changing the partition type. When changing
                the partition type, DiskPart will attempt to lock and dismount
                the file system on the volume. If this parameter is not specified,
                and the call to lock the file system fails, (because some other
                application has an open handle to the volume), the entire
                operation will fail. When this parameter is specified, the
                dismount is forced even if the call to lock the file system
                fails. When a file system is dismounted, all opened handles to
                the volume will become invalid.

    NOERR       For scripting only. When an error is encountered, DiskPart
                continues to process commands as if the error did not occur.
                Without the NOERR parameter, an error causes DiskPart to exit
                with an error code.

    Intended for Original Equipment Manufacturer (OEM) use only.

    A partition must be selected for this operation to succeed.

    Caution:

        Changing partition type fields with this parameter might cause your
        computer to fail or be unable to start up. Unless you are an OEM or an
        IT professional experienced with GPT disks, do not change partition
        type fields on GPT disks using this parameter. Instead, always use the
        CREATE PARTITION EFI command to create EFI System partitions, the
        CREATE PARTITION MSR command to create Microsoft Reserved partitions,
        and the CREATE PARTITION PRIMARY command without the ID parameter to
        create primary partitions on GPT disks.

    This command does not work on dynamic disks nor on Microsoft Reserved
    partitions.

    Example:

    SET ID=07 OVERRIDE
    SET ID=ebd0a0a2-b9e5-4433-87c0-68b6b72699c7

DISKPART> SET ID=ebd0a0a2-b9e5-4433-87c0-68b6b72699c7

DiskPart successfully set the partition ID.

DISKPART> extend

DiskPart successfully extended the volume.

DISKPART> set id=c12a7328-f81f-11d2-ba4b-00a0c93ec93b

DiskPart successfully set the partition ID.

DISKPART> format fs=fat32 label=EFI quick

  100 percent completed

DiskPart successfully formatted the volume.

DISKPART> assign letter=s

DiskPart successfully assigned the drive letter or mount point.

DISKPART> exit

Leaving DiskPart...

X:\windows\system32>xcopy c:\drive_s\* s:\ /e /h
C:\drive_s\EFI\Boot\bootx64.efi
C:\drive_s\EFI\Microsoft\Boot\BCD
C:\drive_s\EFI\Microsoft\Boot\BCD.LOG
C:\drive_s\EFI\Microsoft\Boot\BCD.LOG1
C:\drive_s\EFI\Microsoft\Boot\BCD.LOG2
C:\drive_s\EFI\Microsoft\Boot\boot.stl
C:\drive_s\EFI\Microsoft\Boot\bootmgfw.efi
C:\drive_s\EFI\Microsoft\Boot\bootmgr.efi
C:\drive_s\EFI\Microsoft\Boot\BOOTSTAT.DAT
C:\drive_s\EFI\Microsoft\Boot\kdstub.dll
C:\drive_s\EFI\Microsoft\Boot\kd_02_10df.dll
C:\drive_s\EFI\Microsoft\Boot\kd_02_10ec.dll
C:\drive_s\EFI\Microsoft\Boot\kd_02_1137.dll
C:\drive_s\EFI\Microsoft\Boot\kd_02_14e4.dll
C:\drive_s\EFI\Microsoft\Boot\kd_02_15b3.dll
C:\drive_s\EFI\Microsoft\Boot\kd_02_1969.dll
C:\drive_s\EFI\Microsoft\Boot\kd_02_19a2.dll
C:\drive_s\EFI\Microsoft\Boot\kd_02_1af4.dll
C:\drive_s\EFI\Microsoft\Boot\kd_02_8086.dll
C:\drive_s\EFI\Microsoft\Boot\kd_07_1415.dll
C:\drive_s\EFI\Microsoft\Boot\kd_0C_8086.dll
C:\drive_s\EFI\Microsoft\Boot\memtest.efi
C:\drive_s\EFI\Microsoft\Boot\winsipolicy.p7b
C:\drive_s\EFI\Microsoft\Boot\bg-BG\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\bg-BG\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\cs-CZ\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\cs-CZ\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\cs-CZ\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\da-DK\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\da-DK\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\da-DK\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\de-DE\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\de-DE\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\de-DE\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\el-GR\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\el-GR\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\el-GR\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\en-GB\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\en-GB\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\en-US\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\en-US\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\en-US\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\es-ES\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\es-ES\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\es-ES\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\es-MX\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\es-MX\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\et-EE\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\et-EE\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\fi-FI\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\fi-FI\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\fi-FI\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\Fonts\chs_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\cht_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\jpn_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\kor_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\malgunn_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\malgun_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\meiryon_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\meiryo_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\msjhn_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\msjh_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\msyhn_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\msyh_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\segmono_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\segoen_slboot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\segoe_slboot.ttf
C:\drive_s\EFI\Microsoft\Boot\Fonts\wgl4_boot.ttf
C:\drive_s\EFI\Microsoft\Boot\fr-CA\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\fr-CA\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\fr-FR\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\fr-FR\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\fr-FR\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\hr-HR\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\hr-HR\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\hu-HU\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\hu-HU\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\hu-HU\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\it-IT\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\it-IT\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\it-IT\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ja-JP\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ja-JP\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ja-JP\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ko-KR\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ko-KR\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ko-KR\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\lt-LT\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\lt-LT\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\lv-LV\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\lv-LV\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\nb-NO\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\nb-NO\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\nb-NO\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\nl-NL\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\nl-NL\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\nl-NL\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\pl-PL\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\pl-PL\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\pl-PL\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\pt-BR\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\pt-BR\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\pt-BR\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\pt-PT\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\pt-PT\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\pt-PT\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\qps-ploc\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\Resources\bootres.dll
C:\drive_s\EFI\Microsoft\Boot\Resources\en-US\bootres.dll.mui
C:\drive_s\EFI\Microsoft\Boot\ro-RO\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ro-RO\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ru-RU\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ru-RU\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\ru-RU\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\sk-SK\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\sk-SK\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\sl-SI\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\sl-SI\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\sr-Latn-RS\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\sr-Latn-RS\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\sv-SE\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\sv-SE\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\sv-SE\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\tr-TR\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\tr-TR\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\tr-TR\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\uk-UA\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\uk-UA\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\zh-CN\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\zh-CN\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\zh-CN\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Boot\zh-TW\bootmgfw.efi.mui
C:\drive_s\EFI\Microsoft\Boot\zh-TW\bootmgr.efi.mui
C:\drive_s\EFI\Microsoft\Boot\zh-TW\memtest.efi.mui
C:\drive_s\EFI\Microsoft\Recovery\BCD
C:\drive_s\EFI\Microsoft\Recovery\BCD.LOG
C:\drive_s\EFI\Microsoft\Recovery\BCD.LOG1
C:\drive_s\EFI\Microsoft\Recovery\BCD.LOG2
138 File(s) copied

X:\windows\system32>rd /s /q c:\drive_s

X:\windows\system32>exit

Can we merge disk0s1 and disk0s2 into a single EFI partition? Would that work? I don't care for a windows recovery partition. Would I have to re-enumerate the partitions manually using the 'gpt' command line tool if we go down this path? I hope it won't cause Windows to stop booting after that. Thanks for taking the time to look into this btw. Appreciate it :) — XDS, Commented Dec 28, 2018 at 0:11
Mac OS High Sierra installer is working its magic as we speak! You totally nailed it - hats off to you man! — XDS, Commented Dec 28, 2018 at 23:04

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Attempting to install High Sierra alongside Windows 10 (1809 October 2018 ISO): "This disk cannot be used to startup your computer"

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Steps to merge `disk0s1` and `disk0s2` into a single EFI partition.

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Attempting to install High Sierra alongside Windows 10 (1809 October 2018 ISO): "This disk cannot be used to startup your computer"

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Steps to merge disk0s1 and disk0s2 into a single EFI partition.

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Steps to merge `disk0s1` and `disk0s2` into a single EFI partition.

Not the answer you're looking for? Browse other questions tagged
mac
high-sierra
windows
install
dual-boot
.