Installing Win 10

[vulgo]

And tricky part is you must the disconnect your OSX drive first

Believe OP is using the one drive.

edit - no they aren't OP has 2 drives. even so, physically removing anything not required

 

[vulgo]

So I downloaded a free trial of Paragon to format it as NTFS, but Windows still can't install on it because it is MBR, not GPT.

This is due to a bug where the installer refuses to install to an MBR formatted disk when started from UEFI. You can:

a) Back up your data, reformat your drive GPT, re-install macOS and continue to install windows.

OR

b) Re-create your bootable windows 10 install media the MBR way by "burning" or "restoring" the ISO to a USB flash drive, and continue to install windows.

edit: Note that going option b way, the installer may overwrite your bootloader so have a clover USB handy so you can boot into macOS and re-install the bootloader to your system disk.

edit 2: with the first one- if macOS is on a different disk there is no need to reinstall it

 

[awesomeepicguy]

This is due to a bug where the installer refuses to install to an MBR formatted disk when started from UEFI. You can:

a) Back up your data, reformat your drive GPT, re-install macOS and continue to install windows.

OR

b) Re-create your bootable windows 10 install media the MBR way by "burning" or "restoring" the ISO to a USB flash drive, and continue to install windows.

edit: Note that going option b way, the installer may overwrite your bootloader so have a clover USB handy so you can boot into macOS and re-install the bootloader to your system disk.

edit 2: with the first one- if macOS is on a different disk there is no need to reinstall it

How can I reformat the drive as GPT?

I checked the drive in Disk Utility, it is already listed as GUID Partition Map.

 

[vulgo]

How can I reformat the drive as GPT?

I checked the drive in Disk Utility, it is already listed as GUID Partition Map.

Did you create the partition with bootcamp? Take a look at this

 

[awesomeepicguy]

Did you create the partition with bootcamp? Take a look at this

Right now there is no partition for Windows. But when I make one, it doesn't tell me whether the partition itself is GPT or MBR. It only says whether the drive is GPT.

Is there any way to create a GPT disk without using Disk Utility or Bootcamp?

See here:

 

[vulgo]

Is there any way to create a GPT disk without using Disk Utility or Bootcamp?

Use HFS+ to allocate the space. Without the hybrid MBR the windows should give you the option to initialise the partition as NTFS.

 

[awesomeepicguy]

Use HFS+ to allocate the space. Without the hybrid MBR the windows should give you the option to initialise the partition as NTFS.

So basically format the partition as MacOS Extended (Journaled)?

 

[m0reilly]

wow, this is becoming the most complicated windows installation i have ever heard of...

 

[vulgo]

So basically format the partition as MacOS Extended (Journaled)?

Yes

 

[awesomeepicguy]

It gave me the same message as before: