Reinstalling Windows though BOOTCAMP yields "We couldn't create a new partition or locate an existing one. Form more information, see setup log files"

Thank you for your amazing explanation!

Prior to your response, I have gone through the gdisk command-set as you have posted for other threads. (The only change is the non-default for gpt partition 4 where I have entered '0c' ... as well, i didn't always see an appropriate prompt for when you asked to hit 'O - print the current Hybrid MBR')

Here are the results of this sequence:

Last login: Mon Jul 20 00:03:41 on ttys000

Toms-Mac-mini:~ tomkenna$ sudo gdisk /dev/disk1

GPT fdisk (gdisk) version 1.0.0

Warning: Devices opened with shared lock will not have their

partition table automatically reloaded!

Partition table scan:

MBR: protective

BSD: not present

APM: not present

GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): P

Disk /dev/disk1: 3907029168 sectors, 1.8 TiB

Logical sector size: 512 bytes

Disk identifier (GUID): E84C0D3F-7F5F-4192-B4BC-A656CA1C3A6A

Partition table holds up to 128 entries

First usable sector is 34, last usable sector is 3907029134

Partitions will be aligned on 8-sector boundaries

Total free space is 269 sectors (134.5 KiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 3722805351 1.7 TiB AF05 Macintosh HD

3 3722805352 3724074887 619.9 MiB AB00 Recovery HD

4 3724075008 3907028991 87.2 GiB 0700 BOOTCAMP

Command (? for help): R

Recovery/transformation command (? for help): H

WARNING! Hybrid MBRs are flaky and dangerous! If you decide not to use one,

just hit the Enter key at the below prompt and your MBR partition table will

be untouched.

Type from one to three GPT partition numbers, separated by spaces, to be

added to the hybrid MBR, in sequence: 2 3 4

Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y

Creating entry for GPT partition #2 (MBR partition #2)

Enter an MBR hex code (default AF): AF

Set the bootable flag? (Y/N): n

Creating entry for GPT partition #3 (MBR partition #3)

Enter an MBR hex code (default AB): AB

Set the bootable flag? (Y/N): n

Creating entry for GPT partition #4 (MBR partition #4)

Enter an MBR hex code (default 07): 0c

Set the bootable flag? (Y/N): Y

Recovery/transformation command (? for help): P

Disk /dev/disk1: 3907029168 sectors, 1.8 TiB

Logical sector size: 512 bytes

Disk identifier (GUID): E84C0D3F-7F5F-4192-B4BC-A656CA1C3A6A

Partition table holds up to 128 entries

First usable sector is 34, last usable sector is 3907029134

Partitions will be aligned on 8-sector boundaries

Total free space is 269 sectors (134.5 KiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 3722805351 1.7 TiB AF05 Macintosh HD

3 3722805352 3724074887 619.9 MiB AB00 Recovery HD

4 3724075008 3907028991 87.2 GiB 0700 BOOTCAMP

Recovery/transformation command (? for help): W

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING

PARTITIONS!!

Do you want to proceed? (Y/N): Y

OK; writing new GUID partition table (GPT) to /dev/disk1.

Warning: Devices opened with shared lock will not have their

partition table automatically reloaded!

Warning: The kernel may continue to use old or deleted partitions.

You should reboot or remove the drive.

The operation has completed successfully.

Toms-Mac-mini:~ tomkenna$

I'm going to reboot now and see how things go ... crossing fingers!

So, unfortunately, it doesn't appear I am able to test. This has happened to me in earlier troubleshooting of this problem. The only time it ever boots into the installation screen is RIGHT AFTER BootCamp partitions the drive and reboots the machine itself.

When I reboot, I'll hold down the Alt key and see the usual: "Macintosh HD", "Windows", "EFI Boot"(or something similar). If I select either 'Windows' or 'efi boot', the screen will go pitch-black and not seem to recover. (When I select 'Windows', I *do* see the Windows logo for a few seconds, then when the 'circle-beeds' new-fanged hourglass just starts to come up, the whole screen goes black. During one bout, I let this go for 40minutes and did not see a change. I usually will just hard-boot out of it, but I can also hit the Esc key once or twice and it will reboot as well.

One time, I rebooted and forgot to hold the Alt key and it went right into the windows installation. That time, obviously, i didn't get the black screen, but i have not been able to recreate this. Without holding Alt, it goes right to OS X.

For the heck of it, here are the sudo command results for disk1:

Last login: Mon Jul 20 00:24:38 on console

Toms-Mac-mini:~ tomkenna$ sudo gpt -vv -r show /dev/disk1

Password:

gpt show: /dev/disk1: mediasize=2000398934016; sectorsize=512; blocks=3907029168

gpt show: /dev/disk1: Suspicious MBR at sector 0

gpt show: /dev/disk1: Pri GPT at sector 1

gpt show: /dev/disk1: Sec GPT at sector 3907029167

start size index contents

0 1 MBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

409640 3722395712 2 GPT part - 53746F72-6167-11AA-AA11-00306543ECAC

3722805352 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

3724074888 120

3724075008 182953984 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

3907028992 143

3907029135 32 Sec GPT table

3907029167 1 Sec GPT header

Toms-Mac-mini:~ tomkenna$ sudo fdisk /dev/disk1

Disk: /dev/disk1 geometry: 243201/255/63 [3907029168 sectors]

Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 0 0 2 - 25 127 14 [ 1 - 409639] <Unknown ID>

2: AF 25 127 15 - 1023 254 63 [ 409640 - 3722395712] HFS+

3: AB 1023 254 63 - 1023 254 63 [3722805352 - 1269536] Darwin Boot

*4: 0C 1023 254 63 - 1023 254 63 [3724075008 - 182953984] Win95 FAT32L

Toms-Mac-mini:~ tomkenna$

[deleted - duplicate]

Reset SMC & NVRAM, ran gdisk (this time w/ second printout so you can see sector codes) and made part 4 non-bootable, here is the output:

Last login: Mon Jul 20 01:45:23 on console

Toms-Mac-mini:~ tomkenna$ sudo gdisk /dev/disk1

Password:

GPT fdisk (gdisk) version 1.0.0

Warning: Devices opened with shared lock will not have their

partition table automatically reloaded!

Partition table scan:

MBR: hybrid

BSD: not present

APM: not present

GPT: present

Found valid GPT with hybrid MBR; using GPT.

Command (? for help): P

Disk /dev/disk1: 3907029168 sectors, 1.8 TiB

Logical sector size: 512 bytes

Disk identifier (GUID): E84C0D3F-7F5F-4192-B4BC-A656CA1C3A6A

Partition table holds up to 128 entries

First usable sector is 34, last usable sector is 3907029134

Partitions will be aligned on 8-sector boundaries

Total free space is 269 sectors (134.5 KiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 3722805351 1.7 TiB AF05 Macintosh HD

3 3722805352 3724074887 619.9 MiB AB00 Recovery HD

4 3724075008 3907028991 87.2 GiB 0700 BOOTCAMP

Command (? for help): R

Recovery/transformation command (? for help): H

WARNING! Hybrid MBRs are flaky and dangerous! If you decide not to use one,

just hit the Enter key at the below prompt and your MBR partition table will

be untouched.

Type from one to three GPT partition numbers, separated by spaces, to be

added to the hybrid MBR, in sequence: 2 3 4

Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y

Creating entry for GPT partition #2 (MBR partition #2)

Enter an MBR hex code (default AF):

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #3 (MBR partition #3)

Enter an MBR hex code (default AB):

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #4 (MBR partition #4)

Enter an MBR hex code (default 07):

Set the bootable flag? (Y/N): N

Recovery/transformation command (? for help): O

Disk size is 3907029168 sectors (1.8 TiB)

MBR disk identifier: 0xF194F527

MBR partitions:

Number Boot Start Sector End Sector Status Code

1 1 409639 primary 0xEE

2 409640 3722805351 primary 0xAF

3 3722805352 3724074887 primary 0xAB

4 3724075008 3907028991 primary 0x07

Recovery/transformation command (? for help): W

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING

PARTITIONS!!

Do you want to proceed? (Y/N): Y

OK; writing new GUID partition table (GPT) to /dev/disk1.

Warning: Devices opened with shared lock will not have their

partition table automatically reloaded!

Warning: The kernel may continue to use old or deleted partitions.

You should reboot or remove the drive.

The operation has completed successfully.

Toms-Mac-mini:~ tomkenna$

rebooting now ... will let you know how it goes ✅

rebooted, selected EFIBoot -- black screen

SMC & NVRAM reset

rebooted, selected WININSTALL -- black screen (something a bit different this time -- it did NOT show the Windows icon for prior to going black ... just straight to a black screen)

Is it possible the that Format to NTFS in the Windows install removes display drivers? I can't explain why, when I let BootCamp reboot the machine directly to the Windows installation after partitioning, there are no problems with the display. The minimum event I've ever performed prior to rebooting was just the NTSF Formatting of Partition 4, but after which, a reboot and selecting WININSTALL or EFIBoot will always eventually get me a black screen.

Thank you for your response, Loner. Unfortunately, the late 2014 mini only has TB and an HDMI (presumably this is the same as DP?) connectors. I can try hooking up my TV to the HDMI port if you think that would help, but I'm currently using the ThunderBolt direct connection to an Apple Display monitor, which, according to your experiences, could explain the issue. Again, no issues whatsoever the first time I installed, but I understand that with whatever "changed" here, everything is off the table.

I can try the HDMI port, or I'm willing to purchase an adapter and try an older vga/svga monitor i think i have hanging around. Thoughts? (As always, thank you!!)

99% there!

So plugging in an HDMI cable from the mini to a TV, I was able to get to the install screen (first tried selecting EFI Boot, ran into a strange GPT/MBR error, tried again selecting Windows and was able to select Partition 4 and NO LONGER RECEIVE THE ERROR!)

I was able to install Windows without a hitch! When I got in, I made sure I installed the BootCamp display drivers and run Windows Update, I plugged back in my Apple Display through TB & it rendered perfectly 😍 ... all good!

I thought I was homefree but I'm running into one (hopefully) final issue: When I reboot, i CONTINUE to get a black screen. I can ONLY get windows to work by plugging in the HDMI cable between the mini and TV ... once I log into Windows and wait about a minute or two ... poof! the Apple Display kicks in fine & I can remove the HDMI/TV connection.

Any thoughts on this?

THANK YOU A *THOUSAND* TIMES OVER! You really have been beyond anything I've ever experienced in end-user/community forum support.

So, by a miracle of miracles ... I'm now able to boot into Windows fine ... the screen still goes black, but now only for a moment ... then it goes "blank" (i would describe this different than 'black' as that the monitor is now "on" but not showing anything ... then, POOF! the circling beads "waiting" animation appears in all of its glory.

I've rebooted a few times now, and the "fix" has seemed to have stuck, though honestly I have done, to the best of my recollection, nothing different.

Loner -- you are the Batman of the Apple support community. We don't deserve you -- but, man, do we need you 🙂

I have spent almost 3 solid days on this issue. It has been surreal, but I'm beyond exited to have found resolution and owe it 100% to you. Thank you so much.😎