So - I did it & did survive. I put Z: onto the system partition & did: BCDBoot C:\Windows /s z:/f all /v
(1) It cleaned up my BCD to some extent, but not completely. It left more junk than was removed. I should have renamed the BCD first, I think.
(2) It created a new folder on the system partition called "Boot" which doubled its size.
Directory of z:\
05/09/2017 12:25 AM <DIR> EFI
02/19/2018 10:06 PM <DIR> Boot
02/10/2018 12:37 AM 398,090 bootmgr
09/29/2017 08:41 AM 1 BOOTNXT
2 File(s) 398,091 bytes
I deleted that & the extra copy of BootMGR it had deposited in the root folder. To avoid this, I suggest you use "/f UEFI" - instead of "/f All". That extra stuff was to make the system folder compatible with MBR disks - but we two are both
GPT.
(3) It turned OFF my recovery partition, but I turned it back on with ReagentC.
Here is what it did...
C:\WINDOWS\system32>BCDBoot C:\Windows /s z: /f all /v
BFSVC: ServiceBootFiles MuiOnly:n Res:y Fonts:y BootMgrOvw:n BootStatOvw:n DbgTrn:y SuspendBDE:n
BFSVC: Using source OS version a00003fab000f
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\bootmgr for read because the file or path does not exist
BFSVC: Copying boot files CopyBootManager(Yes) C:\Windows\boot\PCAT -> \?\GLOBALROOT\Device\HarddiskVolume2\Boot
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\bg-BG\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\bootmgr for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\bootvhd.dll for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\cs-CZ\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\cs-CZ\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\da-DK\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\da-DK\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\de-DE\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\de-DE\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\el-GR\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\el-GR\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\en-GB\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\en-US\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\en-US\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\es-ES\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\es-ES\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\es-MX\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\et-EE\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\fi-FI\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\fi-FI\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\fr-CA\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\fr-FR\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\fr-FR\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\hr-HR\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\hu-HU\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\hu-HU\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\it-IT\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\it-IT\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\ja-JP\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\ja-JP\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\ko-KR\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\ko-KR\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\lt-LT\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\lv-LV\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\memtest.exe for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\nb-NO\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\nb-NO\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\nl-NL\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\nl-NL\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\pl-PL\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\pl-PL\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\pt-BR\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\pt-BR\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\pt-PT\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\pt-PT\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\qps-ploc\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\qps-ploc\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\ro-RO\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\ru-RU\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\ru-RU\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\sk-SK\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\sl-SI\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\sr-Latn-RS\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\sv-SE\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\sv-SE\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\tr-TR\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\tr-TR\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\uk-UA\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\zh-CN\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\zh-CN\memtest.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\zh-TW\bootmgr.exe.mui for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\zh-TW\memtest.exe.mui for read because the file or path does not exist
BFSVC: GetFileAttributes(\?\GLOBALROOT\Device\HarddiskVolume2\Boot\BCD) failed: File not found.
BFSVC: GetFileAttributes(\?\GLOBALROOT\Device\HarddiskVolume2\Boot\BCD.LOG) failed: File not found.
BFSVC: Copying font files from C:\Windows\boot\Fonts to \?\GLOBALROOT\Device\HarddiskVolume2\Boot\Fonts...
BFSVC: Copying resource files from C:\Windows\boot\Resources to \?\GLOBALROOT\Device\HarddiskVolume2\Boot\Resources...
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\Resources\bootres.dll for read because the file or path does not exist
BFSVC: Unable to open file \?\GLOBALROOT\Device\HarddiskVolume2\Boot\Resources\en-US\bootres.dll.mui for read because the file or path does not exist
BFSVC: Servicing debugger files
BFSVC: List of debugger files is empty
BFSVC: BfsInitializeBcdStore flags(0x0000021c) RetainElementData:n DelExistinObject:n
BFSVC: VolumePathName for C:\Windows is C:\
BFSVC: Opening template from \Device\HarddiskVolume4\Windows\System32\config\BCD-Template.
BFSVC: Opening store from \Device\HarddiskVolume2\boot\BCD
BFSVC: System BCD store does not exist, creating.
BFSVC: Creating General objects.
BFSVC: Creating Resume object.
BFSVC: Creating MemTest object.
BFSVC: Creating OsLoader object.
BFSVC: OsLoader identifier: {12559446-15eb-11e8-b080-74e6e2074932}
BFSVC: Removing duplicate entries.
BFSVC: Create BOOTMGR object RetainBootDefault:n
BFSVC: Setting {default} to {12559446-15eb-11e8-b080-74e6e2074932}
BFSVC: Cleaning up debugger settings.
BFSVC: ServiceBootFiles MuiOnly:n Res:y Fonts:y BootMgrOvw:n BootStatOvw:n DbgTrn:y SuspendBDE:n
BFSVC: Using source OS version a00003fab000f
BFSVC: Copying boot files CopyBootManager(Yes) C:\Windows\boot\EFI -> \?\GLOBALROOT\Device\HarddiskVolume2\EFI\Microsoft\Boot
BFSVC: Creating Recovery directory.
BFSVC: Copying font files from C:\Windows\boot\Fonts to \?\GLOBALROOT\Device\HarddiskVolume2\EFI\Microsoft\Boot\Fonts...
BFSVC: Copying resource files from C:\Windows\boot\Resources to \?\GLOBALROOT\Device\HarddiskVolume2\EFI\Microsoft\Boot\Resources...
BFSVC: Servicing debugger files
BFSVC: Copying boot debugging files from C:\Windows\system32 to \?\GLOBALROOT\Device\HarddiskVolume2\EFI\Microsoft\Boot (kd_*_*.dll)
BFSVC: Copying boot debugging files from C:\Windows\system32 to \?\GLOBALROOT\Device\HarddiskVolume2\EFI\Microsoft\Boot (kdstub.dll)
BFSVC: Done servicing debugger files.
BFSVC: BfsInitializeBcdStore flags(0x0000021c) RetainElementData:n DelExistinObject:n
BFSVC: VolumePathName for C:\Windows is C:\
BFSVC: Opening template from \Device\HarddiskVolume4\Windows\System32\config\BCD-Template.
BFSVC: Opening store from \Device\HarddiskVolume2\EFI\Microsoft\Boot\BCD
BFSVC: Creating General objects.
BFSVC: Creating Resume object.
BFSVC: Creating MemTest object.
BFSVC: Creating OsLoader object.
BFSVC: OsLoader identifier: {1669dd2e-15eb-11e8-b080-74e6e2074932}
BFSVC: Removing duplicate entries.
BFSVC: Removing duplicate object {140ab405-3491-11e7-a4a0-952787f57a8e}
BFSVC: Removing duplicate object {7254a080-1510-4e85-ac0f-e7fb3d444736}
BFSVC: Create BOOTMGR object RetainBootDefault:n
BFSVC: Setting {default} to {1669dd2e-15eb-11e8-b080-74e6e2074932}
BFSVC: Cleaning up debugger settings.
BFSVC: Opening recovery store from \Device\HarddiskVolume2\EFI\Microsoft\Recovery\BCD
BFSVC: Creating General objects.
BFSVC: Create BOOTMGR object RetainBootDefault:y
BFSVC: Setting {default} to {f12321ae-b3ff-11e7-9217-d7700d4f6e45}
Boot files successfully created.
C:\WINDOWS\system32>