We couldn’t create a new partition or locate an existing one, possible workarounds


One of the consequences of being part of the Windows Insiders program is that occasionally you run into a bug so bad that your system doesn't boot. Fortunately, the kernel team was able to diagnose the problem on my machine and develop a fix.

The fix was too late for me, but at least it will be useful to others. In the meantime, I had to reinstall my system. I waited for the fix to be released and copied the build to a bootable USB thumb drive. I booted from that thumb drive and told Windows to install to the partition that held my previous (broken) Windows installation.

And that's where I got the error "We couldn't create a new partition or locate an existing one."

The Setup team told me that Setup wants a System partition, and one way to make this possible is to shrink an existing partition by around 500MB. But my machine already had a System partition. After all, it's being used by the existing Windows installation.

We played around and concluded that Setup was getting confused over which volume was the boot volume, and it may be trying to treat the USB thumb drive as the boot volume and trying to create a System partition on it.

Here's the solution: At the initial Setup dialog box, do not click Install Windows. Instead, press Shift+F10. This will open a command prompt.

Use the command prompt to copy the contents of the thumb drive to a directory in the root of disk 0. The drive letter for disk 0 will vary, so let's say it's X:, and for concreteness, let's call the directory X:\media.

Once the contents have been copied, remove the USB thumb drive, and reverify that you are on the initial dialog box. (If you accidentally proceeded past it, then click Back to get back to it.) Then run X:\media\sources\setup.exe.

There are actually two Setup programs. The first one is setup.exe in the root of the install media. This is the Setup introductory dialog.

If you click Install, then it runs sources\setup.exe, which is the main Setup program.

Each Setup program detects that a copy of itself is already running and will hand control over to the existing copy.

This means that running X:\media\setup.exe will not work because it will detect is already-running copy and hand control to it.

You have to make sure that you haven't clicked the Install button in the initial setup dialog, and then run the Setup program in the sources subdirectory.

And don't forget to remove the USB thumb drive before you run X:\media\sources\setup.exe. Otherwise, it will see the thumb drive and get confused again.

There are other ways to solve the problem, but this one seemed the most straightforward. Basically, you first want to boot Windows off something. A USB bootable drive is most convenient, but a network (PXE) boot or a bootable CD will also work. Next, remove all storage drives except the one you want to install from. That way Setup won't get confused. And finally, run sources\setup.exe to get the party started.

It worked for me. Maybe it'll work for you.

Comments (26)
  1. kantos says:

    This should be in the knowledge base

    1. Nick says:

      It really shouldn’t. Problems like this should be solved well before the general public could see them. If anywhere, it belongs in the blog posts announcing new Insider builds, likely as a link to this blog post.

      1. kantos says:

        I respectfully disagree, there are a lot of reasons that installs get corrupted. Everything from bad updates to a power outage. Like or not heavy duty recoveries like this do happen all the time. More often than not by just mounting the drive on another computer and then copying off data. Doing it this way prevents that from even being necessary. While in a perfect world an install would never get corrupted that’s just not realistic.

        1. Beldantazar says:

          This isn’t just a corrupted install issue, though, this is the installer being unable to understand the drives properly so you can select one to install. And that is a problem that definitely should never be able to get out to any users not in the insider program.

    2. Marc says:

      >> This should be in the knowledge base
      I agree – but have you ever seen ANYTHING in the knowledge base that was as clear and informative as one of Raymond’s write-ups? Sometimes it seems that the KB is where knowledge goes to die.

  2. Antonio Rodríguez says:

    The ability to immediately launch a command prompt pressing Shift+F10 is a neat trick. The visible way (going through the repair options) is slow because it tries to auto-dectect all Windows installations, and may fail if the disk is so wrecked it doesn’t detect Windows.

    1. cheong00 says:

      This reminds me the experience that once upon a time, when I need to install Linux on some disk connecting to RAID card, I have to Ctrl-Alt-F3 to switch to the shell, mount driver disk and copy to ramdisk, then insmod some drivers before continue.

      Cool thing you can fire up a shell to fix something to allow installer to continue.

  3. Joshua says:

    It is now. The Old New Thing is the better knowledge base.

    1. cheong00 says:

      Agreed, in the sense that at least during each blog website upgrade/migration, they remember to fix the links and/or use rewrite like modules to keep the old link work.

      There are a number of KB simply disappeared without anything like saying the article is retired or something.

      1. Erik F says:

        That’s mostly true: links in comments don’t seem to get fixed, and really old asp.net links are broken everywhere. That’s not bad though, compared to the link rot that I see in a lot of other sites!

      2. skSdnW says:

        And even worse, support.microsoft.com switched to horrible AJAX pages a while ago and archive.org is unable to save those pages so all recent KB content is lost forever when something is retired/deleted.

      3. Antonio Rodríguez says:

        Microsoft really should convert some blog entries into KB articles. Authors like Raymond Chen, Eric Lippert (which sadly is no more at Microsoft), Larry Osterman and Aaron Margosis come to mind.

        Oh, and as pointed by skSdnW, the entire knowledge base should be mirrored in Archive.org.

        1. Alex Cohn says:

          And the awesome corpus of Michael Kaplan’s articles on characters, languages, et al

  4. Mantas says:

    A full reinstall? Ouch. We public build users are lucky; only ever need minor fixes such as rebuilding the bootloader twice daily. *cough*

    These kinds of posts are really useful, I’d practically forgotten about Shift+F10. I wonder if there’s another hidden shortcut for making the OS upgrade process more verbose; watching the spinner go from 0% to 100% is a bit like watching paint dry.

    Nitpicker’s corner: Isn’t drive letter X: reserved for the thumbdrive itself?

  5. Roger says:

    Hopefully the Windows setup team can have a look at what Linux distros do for their install media these days. The same binary image can be written directly to a USB stick or a CD, and it just boots. On a UEFI system (including mac oddities) it boots as EFI. On BIOS systems it boots as BIOS mode. It quite simply just works. (You can even loopback mount the image and do PXE netbooting off it too!)

    Windows is especially frustrating. For example if you have a cd image (which is usually all you get to download) then quite a few hoops have to be jumped through to turn it into a UEFI bootable USB stick. Various tools operate on partitions which makes it more complicated to setup the partitioning and boot sectors.

    1. ender9 says:

      From Vista onwards, it’s actually been really simple to create bootable Windows USB sticks – copy the content of ISO to USB stick, and 90% of the time it’ll just work. If it doesn’t, check the following:
      – for BIOS booting, run X:\boot\bootsect.exe /nt60 /mbr X: (replace X: with the actual drive letter; this is only required if the stick was previously formatted with something that’s not Vista or newer; filesystem can be FAT32 or NTFS – either will work)
      – for UEFI booting, make sure that the stick is FAT32-formatted, because that’s the only filesystem the firmware is guaranteed to support

      1. Roger says:

        I don’t call that “really simple”! Having to get partition types and formatting right, and especially the BIOS boot dance is a pain. Testing is also frustrating since the usual symptom is not showing in boot selection menus or just not booting without useful diagnostics. Or it booting in BIOS mode when you wanted UEFI. The Linux “this image just works” is considerably more simple and not prone to those kind of errors.

  6. I’ve run into situations like this. Other solutions for me have been: Make sure extraneous devices aren’t in the bootable devices in the BIOS/UEFI. Sometimes a USB drive will sneak its way in front of the desired boot device. This doesn’t seem to be a problem for an existing installation, but Setup doesn’t handle that situation well. I’ve also run into the issue of booting off the USB/CD in the wrong mode… trying to install UEFI without booting UEFI or vice versa. That’s more a UEFI/BIOS interface issue in conjunction with user error.

  7. Erik F says:

    A few Fast updates ago, I had just been letting Windows rename its old stuff (Windows.000, Windows.001, etc.) until one of the builds apparently decided “that’s enough” and decided to toast all the files from the Windows.002 directory (including my Users directory!) I still haven’t located all of the files that it trashed. Lesson learned: make more backups (always good advice), and don’t trust the installer to keep stuff!

  8. MarcK4096 says:

    I’ve run into this problem installing Windows Server 2012 and 2012 R2. So, it’s not an insider thing. (And yes it should have been fixed long ago.) I wish this article had come out earlier so I knew about shift F10. I wasted a lot of time the first time this happened to me.

    Other work-arounds I found are to use a CD instead of a USB disk or to explicitly boot UEFI. I recently encountered this problem installing Server 2012 R2. Booting legacy resulted in the partition problem. Booting UEFI allowed the install to proceed without issue. Next time, I’ll try shift-F10.

  9. Swisstone says:

    The Setup team should add an additionnal check and exclude drives where the removable flag is set.

  10. Neil says:

    Windows thought that the drive you booted from was your boot drive… why is this surprising?

  11. Keith Davis says:

    I just had this issue a couple of weeks ago and ended up having to delete all partitions and starting from scratch! Anyway, good to have this info for the next time it occurs. Thanks.

  12. Okay, now that I am less likely to attract unwanted attention, here are a couple of tips for improving future posts:

    1. When it comes to Windows Setup, please never use X to refer to either the bootloader or the OS volumes. X is reserved for the RAM disk. I’d use [Vol:] but C is always okay too.
    2. When using the terms “System partition” or “Boot partition” please specify whether you mean the globally accepted meaning or the Microsoft meaning. Or, better yet, consider using “Bootloader’s partition” and “OS partition” instead.

  13. farseerfc says:

    I encountered this problem with win10 setup several times, and get to learn install win10 by disasm manually. never had this problem with win7 installer through

  14. Wow, I actually ran into this issue. Considering the timing and the fact I’m also an insider, I think I actually hit the exact same bug. [Happened when trying to install 17604, which got out six days before this post]

    I deleted all partitions and was left with only unallocated space, but the setup [also running off a USB drive] still couldn’t create a partition.

    I ended up going to cmd and creating one from there and reentering setup. The partition creating via cmd still wouldn’t work, but now deleting and creating a new one did.

    This is a very helpful post. [Although, admittedly, I wouldn’t have reached it in time anyway.]

Comments are closed.

Skip to main content