Convert disk from MBR to GPT without formatting and/or force Windows to install on an EFI system with MBR format

[WhitetailAni]

I'm attempting to install Windows on my MBP, but the disk has a partition table in MBR format, and Windows refuses to install unless I use GPT. The only ways online I've found are by formatting, but I don't have a way to back up my data as I don't have any available storage devices.

Is there a way to do this? From my limited understanding it shouldn't be that hard; the partition table is just a directory for where partitions are as far as I know.

 

Alternatively, is there a way to force Windows to install on an MBR disk on an EFI system?

[Windows7ge]

Take a look at MiniTool Partition Wizard. If I'm not mistaken it should be able to do that.

[Uptivuptiz]

To convert a MBR disk to GPT you can use a tool called MBR2GPT that is made by Microsoft. This is a command line tool though, so if you want something easier to use I recommend downloading Minitool Partition Wizard and following their guide.

[da na]

Very simple with these commands run as an admin.

DISKPART

LIST DISK

SELECT DISK (letter)

CLEAN (erases data, I've always done this before convert but try without it may work)
CONVERT GPT

then you can use format commands but you don't really need to 

[WhitetailAni]

5 minutes ago, Windows7ge said:

Take a look at MiniTool Partition Wizard. If I'm not mistaken it should be able to do that.

I should clarify, I currently only can run macOS. Windows will not install.

5 minutes ago, Uptivuptiz said:

To convert a MBR disk to GPT you can use a tool called MBR2GPT that is made by Microsoft. This is a command line tool though

I'm not scared of CLI. Just to be sure, I can run this from a Windows install USB, and the command I want is this?

MBR2GPT /convert

[Windows7ge]

4 minutes ago, FakeKGB said:

I should clarify, I currently only can run macOS. Windows will not install.

No Windows PC around you could pop it into as a extra drive? Or is the SSD soldered?

[Uptivuptiz]

5 minutes ago, FakeKGB said:

I'm not scared of CLI. Just to be sure, I can run this from a Windows install USB, and the command I want is this?

MBR2GPT /convert

To quote the documentation: 

Quote

The tool is designed to be run from a Windows Preinstallation Environment (Windows PE) command prompt, but can also be run from the full Windows 10 operating system (OS) by using the /allowFullOS option.

And yes, the command you want to run is 

mbr2gpt /convert /disk:INSERT_NUMBER

You can figure out the drive number by using diskpart with this command:

list disk

 

[WhitetailAni]

14 minutes ago, Windows7ge said:

No Windows PC around you could pop it into as a extra drive? Or is the SSD soldered?

I am dumb, I do in fact.

[Windows7ge]

1 minute ago, FakeKGB said:

I am dumb, I do in fact.

 Don't worry about it. You're not out of the woods yet anyhow. I've seen MiniTool Partition Wizard have a number of nifty little features that you just don't see in Windows default like the ability to reorganize partitions on a disk (not normally possible/available in Windows unless it's in CMD/PowerShell somewhere) and as in your case it claims to be able to convert MBR to GPT while preserving the existing partitions/data. I recall it working for some people.

 

I should look into if it's possible from PowerShell. Could be worthwhile to learn but it may not work if you try to do it to the disk you're booting from.

[WhitetailAni]

Of course the only thing that survived is the thing that had no data on it......

52 minutes ago, Windows7ge said:

while preserving the existing partitions/data

[Windows7ge]

8 minutes ago, FakeKGB said:

Of course the only thing that survived is the thing that had no data on it......

Hmn...I assume these were partitions for MacOS? I probably should have mentioned I never tested it with Apple partitions but last I checked Apple uses FAT32 no? Or have they been using their own proprietary FS?

 

Aside from being a good idea in general if you're going to mess with disk configuration or partitions you should always backup your data. If you don't have anywhere to backup the data to that's a good time to pause and figure out some way of making it happen even if it's as basic as a HDD you pulled out of an office PC. Have that data SOMEWHERE in the event things go wrong.

 

Was the data anything of particular importance or is it just a general inconvenience to retrieve from sources? There's the chance you could recover it but I have no MacOS skills at all so I don't know what tools it has for data recovery.

[WhitetailAni]

33 minutes ago, Windows7ge said:

Or have they been using their own proprietary FS?

They've been using their own proprietary FS since the original Macintosh

34 minutes ago, Windows7ge said:

Was the data anything of particular importance or is it just a general inconvenience to retrieve from sources?

I have no available storage devices for backups, otherwise I would have made one. Most of the data is stuff I made with no way to recover; my dad's on his way home from work and is going to help