Windows 10 Changing Windows system/installation label to C:

Hi guys,

I am in dire need of some help/advice.

My parents are on vacation and I thought I would finally upgrade my mother's PC. This PC was still running on Windows XP along with several old programs. Normally I would do a clean install, however she wanted to keep everything *sigh*

So first I cloned the drive to a SSD and placed it into a newer PC. It was a miracle that the PC with the cloned SSD booted without BSOD's. I wasn't expecting this. I did have to reinstall most drivers.

Anyways, went from Windows XP > Vista > 7 and now I am going to install Windows 10.
(this way it was possible to keep her programs, settings, etc. but it took a lot of time)

So far all is going well, for one small/minor issue. For some reason, on the old Windows XP installation. The Windows installation & program folders were located on J: partition. I think this had to do with a restore several years ago. Anyways, partition J: is being used as the main Windows partition.

Is it possible to rename it somehow to C: (like a normal Windows installation) and keep all program's she has installed working (including shortcuts)...?

Any advice/ideas on this? If this is not possible without problems, I will just leave it as J:, however I would prefer renaming it to C: instead.

In the meantime I will install Windows 10 and check back on this thread.

Thank you in advance.



Honorable Member
Leave it for the time being, Windows 10 will make new assignments. You only need to reassign if W10 won't install.

Hope all goes well

Thank you for responding. Appreciate it. :)

Well Windows 10 was installed, all original programs are still working as they did under Windows XP (or at least as far as I have tested them. Will have to wait till my mother comes back home obviously).

Anyways, is it a lot of work to get Windows & programs running again from C:
Is there a tool or program out there which can do that?

I remember Acronis having a program which also fixed programs locations etc. when moving a system partition, but I don't remember it correctly as it was years ago. And to be honest; who has Windows and their programs running from a J: partition. :)

If it's too much work, I will keep it as it is, but rather change it (if possible). :)

Thank you once again.



Honorable Member
Sorry, I understood that W7 used the wrong assignments, and that you were about installing W10.
Now I understand that W10 is using those silly drive letters.

I don't know of any tool that can do that, but I am unfamiliar with Acronis. These drive letters may hide everywhere, including in registry keys.

Whatever you try, make a system copy, either with Acronis or with the old W7 'Make System Copy' tool.


Essential Member
Microsoft Community Contributor

It would help if you could make a screen shot of your Disk Management window and post it here so we can see what's happening.

Right click on the start button and select Disk Management.

I assume that Windows 10 is on the C:\ partition.

As long as all the programs are running there's no reason that they need to be installed on drive C:\.

I don't install any of my software in the C:\ partition so that I can quickly create and restore system images. As far as I'm concerned the less stuff on my Windows drive the better.

As far as drive letters you can change them to what ever you want in Disk Management though it can be kind of a hassle if you have drives that already use the letter that you want to change to.

I.e. if you have a J:\ drive and you want it to be D:\ which is already used for a DVD drive or something, then you have to change the D:\ drive to something that's not used and then change the J:\ drive to D:\ etc.

As you can see it can get pretty complicated...

If you post a image from the Snipping Tool like this we will be able to see what's going on.



Honorable Member
Hi Mike,

Reading again through these postings :
I remember Acronis having a program which also fixed programs locations etc. when moving a system partition, but I don't remember it correctly as it was years ago. And to be honest; who has Windows and their programs running from a J: partition.
it looks to me that he don't have C: but that he uses J: ? :(
How on earth can you do that? I am out of ideas. Let's see what the screen dump tells us.


Yes, my mother's PC is using J: as C: drive. So on J: Windows is located as is the "program files" directory.
This happened a few years back, when someone restored a backup.

I managed to update her PC from Windows XP to Windows 7 while maintaining all her programs and settings, however I want to know if it's possible somehow to switch J: back to C: (C: is not being used now). This without losing program's and such.

If this is not possible, then I will just leave it as it is.

PS: thank you for responding!


Honorable Member
Please, could you show us a screendump of the diskmanager, like Mike suggested, it may help.
Maybe someone on this forum has an idea..



Essential Member
Premium Supporter
I am surprised that windows 10 did not automatically reassign to C:
You have already confirmed you have a safe backup/image?

In that case, I would copy the entire contents of J: to C: (I imagine C: has been created)?

Whilst still in the J: OS, download and run a program such as Easybcd and recreate the boot files.

After spending days (first cloning old PC's harddisk to new SSD) followed by installing Windows 10 (Windows XP > Vista > Win 7 > Win 10). I now have run into a big problem.

I was adding a harddisk next to the SSD (which contains the Windows 10 installation) for backup's and pictures. I added the disk, booted to Windows 10, but I couldn't see the harddisk in there (nor Windows' partition manager, nor in EaseUS partition manager). Therefor I decided to shutdown and check in the bios. In there it said the harddisk installed.

So I ran gparted live (from USB) and formated the harddisk (not the SSD ofcourse) to NTFS and rebooted. Here the nightmare starts.

On first boot it said: INACCESSIBLE_BOOT_DEVICE
Same for the 2nd boot. So I decided to re-run gparted live and delete the harddisk / NTFS partition (yes harddisk, not SSD).

But no luck at all. Now I am getting a new error: 0xc0000225
With the message it says it's missing: \WINDOWS\System32\winload.exe

I can only hit "Enter" to retry (nothing happens)
Press "F8" for startup settings (also nothing happens)

I think this happened, because of adding the 2nd harddisk and formatting it to NTFS. Windows boots up and (my guess) makes the new harddisk / partition C:, therefor it cannot find/load Windows and shows the problem above.

Is there a way to solve this? Editing some boot files perhaps?

FYI: I checked the SSD in gparted (didn't make any changes to it) and it did show the (original) 2 partitions; 200 GB (main storage) and the 450 MB (Windows recovery/boot). The Windows installation / upgrade was a normal install, nothing fancy like (U)EFI.

Any ideas on what to do next or modify to make Windows bootable again?

After that we can figure out how I can add the 2nd harddisk without breaking things (if this is even solveable).

Thank you in advance.

//edit I think I have to make some changes to the BCD file, but not sure, in order to fix this problem?

I also ran bcedit /enum all from Windows 10 USB command prompt.

It says device: unknown (for Windows Boot Manager / Windows Boot Loader).
I saw examples online where it should show the partition, for example: partition=C:
...would mean in my case: partition=J:

Right? If this is correct, how do I change this correctly?

Last edited:
To keep the above post clean from multiple edits.

I made a little bit progress. I don't get the blue screen with the previously mentioned messages anymore and I get the Windows loading symbol, however after that the screen is black.

What I did:

bcdedit /store C:\Boot\BCD /set {bootmgr} device partition=C:
bcdedit /store C:\Boot\BCD /set {default} device partition=C:
bcdedit /store C:\Boot\BCD /set {default} osdevice partition=C:
I think I need to use J: instead, however bcdedit doesn't allow me selecting this partition (probably because he sees J: as C: from the command line in Windows Recovery?)


Honorable Member
And for the time being, if you disconnect the HD and leave the SSD in, what happens then?

Black screen may also mean that set up is running, leave it a while

Last edited:
And for the time being, if you disconnect the HD and leave the SSD in, what happens then?

Black screen my also mean that set up is running, leave it a while

Removing the harddisk doesn't do a thing either.

Well okay, I will leave the black screen on for a while. It does load for a few minutes (led light blinking activity), but after a while it stops. Also before it goes to the black and I get the loading Windows 10 screen, it will flash the screen several times (fast) and after that it turns to black, as mentioned. Sigh.

Oh I also bought Easy Recovery Essentials for Windows 10 and ran the automated repair. But the same thing happens as before (black screen). So much for that software fixing issues. :|


I also noticed I could my mouse on the screen (though the screen stays black) so I followed some advice which was posted on the internet about black screen in Windows 10:

firstly wait long enough so the mouse cursor to appear when you move the mouse.
(blank screen with a white mouse cursor)

Then press the space-bar and enter your login password or pin (yes your doing this blind)
It looks like it logged on, because I got a loading icon, however the screen still stays black.
I can still move the mouse cursor though. But it shows a loading symbol sometimes. So I will wait a bit more, until I do something else...

Last edited:


Honorable Member
Have you tried booting in save mode, it will load an other minimal display driver..

Uhmz, how do I boot to safe mode when I get a black screen?
The only thing I can think of is, by editing BCD, which I will do now, because the black screen is getting me nowhere.


Honorable Member
Hence F8 during Post/power on won't work... sigh

F8 doesn't work obviously with Windows 10. So I tried editing BCD to:

bcdedit /set {default} bootmenupolicy legacy
But that didn't help, apparently it doesn't force safe mode.

Also tried:

bcdedit /set {bootmgr} displaybootmenu yes
But it seems to ignore the bootmenu completely? I only get the Windows loading image.

//update #1

Ran Easy Recovery Windows 10 again for automated repair. Then used bcdedit to change displaybootmenu to yes.

Now I got the menu options, selected safe mode (4) and it loaded the black screen again. However when I move the mouse it does show "safe mode" at the corners, but nothing else.

//update #2

Even deleted the hidden / sytem partition on the SSD (through gparted) and had it repaired through Easy Recovery, but still the same issue. Loading screen, followed by blinking/flashing, black screen but with movable mouse. I am starting to run out of ideas here.

Last edited:


Honorable Member
There are system where F8 stil works, and you seem to have entered save mode, but what is going on?

Before going on, can you mount those disks on an other PC and see whether any user file is still readable and can be saved?
If so I am close to saving what can be saved and start a clean install.

# update: it was a laptop, wasn't it? connect an other monitor?

Last edited:
Probably, but that's not the issue. If I have to clone everything again from the old computer and re-install Windows XP > Windows Vista > Windows 7 > Windows 10 all over again, I rather forget about this.

And before you say; yeah, but you can copy everything over 1-on-1 on a working Windows 10 installation, I doubt that's true, because the problem isn't the boatloader, but something else is. I think something got re-assigned inside the Windows 10 installation by adding the harddisk (as I mentioned earlier today).

I need some way to make changes to whatever has been changed in regards to drive letters and how Windows sees it. Don't know if this is even possible. Probably it concerns editing the registry, but dunno. Hope someone can share some insight in this.


Excellent Member
Microsoft Community Contributor
It appears you have gone down the Rabbit hole with that install. You may never be able to get it to work, and if you do it may be so corrupted your mother will not be happy with it.

So, four thoughts:

You should not need to go through Vista to get to Windows 7, XP should be upgradeable to Windows 7.

If you were to clone the drive to another drive on the same system, it may be forced to go back to a C: for a system drive. I have seen cloning operation change the drive letters because it cannot have two C: partitions (or J).

Changing system drive letters on an installed system may have repercussions such as the registry still having the old letters and also boot failures.

But the best, most logical way to go is to do as suggested and perform a clean install of Windows 10. If your mother needs old files they should be available on the old drive or the image. Trying to drag old programs and drivers into Windows 10 is not a good thing to do.

Edit: You could also check the link below, but make sure and read the part concerning when it is possible to change the drive letter. It appears your system would not fit in the possibilities.

Last edited:
This website is not affiliated, owned, or endorsed by Microsoft Corporation. It is a member of the Microsoft Partner Program.