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2 Solutions: Windows 10 Upgrade Couldn’t Update System Reserved Partition

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    Upgrade to Windows 10, we couldn't update the system reserved partition 1 When upgrading to Windows 10 from Windows 7 or Windows 8.1, you may receive the so annoying error message “We couldn’t update the system reserved partition” and have to stop the upgrade with great unwillingness. Well, have you found the exact cause for this error or do you know how to clear the very roadblock for successful upgrade? If you haven’t got any good idea, please read this post, and we will give lots of details, along with 2 solutions which have been proved to work flawlessly.

    2 Possible Reasons Why Windows 10 Upgrade Couldn’t Update System Reserved Partition

    From the descriptive message we know system reserved partition is the very chief culprit. Well then, what’s going on with this partition? After a series of tests we found 2 possible reasons for this error:
    Reason 1: There is something wrong with the file system of system reserved partition.
    Reasons 2: No enough space in system reserved partition for the upgrade.

    Now that the possible reasons have been found, it should be easy to fix the issue: if the error occurs due to file system failure, we can fix it by repairing file system. However, if it is caused by low disk space, the best solution is to enlarge the system reserved partition. Nevertheless, Windows does not provide users with easy-to-use and effective solutions to do these operations, so users had better employ a free third party partitioning program. Fortunately, MiniTool Partition Wizard will bring users great surprise.

    2 Perfect Solutions When Windows 10 Upgrade Couldn’t Update System Reserved Partition

    We have said there are 2 possible reasons for this error, but most of the time users do not know which is the actual reason. Therefore, it is very necessary to view and check properties of the system reserved partition at first:

    Please download MiniTool Partition Wizard Free Edition (freeware) and install it on your computer. Then, run and launch the application to get its main interface shown below:

    Upgrade to Windows 10, we couldn't update the system reserved partition 2

    From the screen above we can see the 350MB partition is marked as system reserved, and it is always the one we are looking for. But sometimes it isn’t shown as system reserved but with other labels. Let’s see the following example.

    Upgrade to Windows 10, we couldn't update the system reserved partition 3

    Here we can see no partition labeled as system reserved. At this time, if users look for target partition via the same standard, definitely they will be in failure. Actually, users had better check partition status rather than label to distinguish system reserved partition from other partitions, and the partition shown as Active & Boot is always the one we are looking for. Therefore, in the screenshot above the partition labeled with RECOVERY is the system reserved partition.

    Tip: on GPT disk, this partition is not called system reserved partition but called EFI system partition or ESP partition:

    Upgrade to Windows 10, we couldn't update the system reserved partition 4

    After the correct partition is found, users need to check its unused space at first. If there is much free space left in the system reserved partition, the most probable reason would be file system issues. Under this situation, please try checking and fixing file system of the system reserved partition in Partition Wizard to solve the problem. In addition, operations to repair file system on GPT disk are nearly the same as those on MBR disk.

    Fix File System When Update Failure Is Caused by File System Issues

    To check and fix file system of the system reserved partition in MiniTool Partition Wizard, users need to appoint this partition with a drive letter at first since it is always without a drive letter. If not, the function “Check File System” function will be invisible. Next, let’s see how to check and fix file system for system reserved partition.

    1.Select the system reserved partition and click “Change Drive Letter” function from the left side to get the following screenshot:

    Upgrade to Windows 10, we couldn't update the system reserved partition 5

    2.Choose an appropriate drive letter for this partition and click “OK” to go back to the main interface.

    3.Click “Apply” button on the top to make this change performed.

    4.Reselect the system reserved partition and choose “Check File System” to get the following window:

    Upgrade to Windows 10, we couldn't update the system reserved partition 6

    5.Choose “Check & fix detected error” since this feature will detect all file system errors and then fix them one after another. After that, as long as we click “Start” button, the process will begin.

    If there are file system errors found and fixed, users can try upgrading to Windows 10 again, and this time it may work. However, if no error is found by MiniTool Partition Wizard or users find there is little or no free space left in the system reserved partition when checking unused space of this partition, users can try enlarging the partition to solve the problem.

    Enlarge System Reserved Partition When Update Failure is Caused by Low Disk Space

    Tip: nowadays, Legacy BIOS + MBR and UEFI + GPT are 2 most commonly seen boot modes on Windows platform. Under different mode operations of extending system reserved partition are little bit different so that we will show detailed steps on both modes.In addition, we highly suggest extending system partition by using MiniTool Partition Wizard Bootable CD (freeware), which performs operations in boot mode so that system security could be ensured.

    Extend System Reserved Partition Under Legacy BIOS + MBR Boot Mode (steps under UEFI + GPT mode will be introduced after this part is over):
    If you are booting Windows from MBR disk, please take the following operations:
    • Download MiniTool Partition Wizard Bootable CD and burn it to CD, DVD, or USB flash drive.
    • Boot computer via the bootable disc.
    • Select the system reserved partition and choose “Extend Partition” feature from the left action panel.
    • Extend the target partition by taking free space from other existing partitions on the same disk and click “OK”.
    • Click “Apply” button on the top to perform all changes.
    After these steps, to increase space for system reserved partition has been completed. For more details, please see Extend Partition.

    Then, it’s time to enlarge EFI system partition on GPT disk.

    Enlarge ESP Partition Under UEFI + GPT Boot Mode:
    For users who are running Windows on GPT disk, they can increase space for the EFI system partition by taking the following operations.

    Firstly, boot computer via MiniTool Partition Wizard Bootable CD to get partition layout:

    Upgrade to Windows 10, we couldn't update the system reserved partition 7

    Here the 500MB ESP partition which is marked as Active & Boot is the very partition we need to enlarge, and now it has no free space available. But fortunately, we can enlarge it by taking free space from any other existing partition which is with recognizable file system (FAT or NTFS) on the same hard disk. For example, we can extend the ESP partition by taking free space from partition C since this partition has 760GB unused space left. Of course, we can also enlarge it by making use of unallocated space if there is such a kind of space.

    However, in the case above, if we want to extend the EFI system partition (ESP) by borrowing free space from partition C, we need to delete the 128MB Microsoft Reserved Partition (MSR partition) at first since it is unrecognizable file system. Well then, does it mean users must delete the MSR partition when they plan to enlarge EFI system partition? Of course not. Actually, only when the MSR partition is located between the EFI system partition and the partition we want to take free space from, the 128MB partition should be deleted. Under this situation, if we do not delete the partition, the extending process will be stopped. For detailed steps to delete an existing partition, please see Delete Partition.

    Tip: deleting the 128MB Microsoft reserved partition does no harm to both data and system, so users can do it without any worries.

    Then, select the EFI system partition and choose “Extend Partition” feature from the left action panel.

    Next, choose partition C from the drop-down list of “Take Free Space from” and then drag sliding handle to decide how much free space to take. Then click “OK” to go back to the main interface.

    At last, click “Apply” button to make all changes performed. After all changes are made, try upgrading Windows 10 again.

    PS. Lots of users have consulted us with the same problem via email, telephone, or online chat, and they finally fixed the error by taking our solutions, so you can also have a try. It brings no damage to both data and system.

    In the end of this post, we would like to share a user comment on Windows 10 upgrading issue (originally posted on one of our pages by Philippe Verdy). His detailed analysis and explanation should be helpful to all of you.

    author Philippe Verdy

    Note that many users have huge problem upgrading to Windows 10 or upgrading to a new image of Windows 10 because of a recurrent failure in its installer to correctly create the recovery partition and boot from it.

    One cause of this not just about other USB devices, or BIOS boot options (MBR vs. UEFI) but the fact that the BCD store frequently contains incorrect information, not updated since long and never changed after Windows upgrades.

    For example I searched for months until I discovered what causes Windows 10 to fail installing new build images, and found that the recovery partition was correct and correct, and had the correct content, but what was wrong was an incorrect setting of the "path" parameter in the BCD store:

    BCDEDIT /enum all

    look for the entry for the Windows Recovery Environment (it does not have a symbolic alias, you can only reference it by its unique {long-guid} in hexadecimal.

    Check the "path" setting, try mounting the Recovery partition (it should be existing and formatted) : look into


    and locate your existing mounted Windows volume (usually mounted on C:)

    select that volume using the displayed number:


    then look at partitions on the same disk:


    You should see an extra (hidden) partition for the Recovery environment, select it by its different number:


    You can see that the correct volume is selected by doing immediately


    where there's an asterisk (*) showing the volume that maps to the partition on disk. This partition should be a NTFS partition of at least 350MB (on my Windows version it requires 300MB to store the Winre.im image file plus some extra files, and with the NTFS structure overhead, it remains about 175MB of free space in it).
    Then mount this volume by assigning a drive letter to it (here R:), and exit DISKPART:


    You can also use the Windows System control panel in the Disk Manager to list partitions, but it does not always show all hidden partitions (for example it does not show the required 100MB partition for the MSR, which contains notably the BCD store on UEFI systems and some boot time maintenance tools not running directly within a normal Windows or Windows PE kernel, such as RAID maintenance tools; it also does not show some OSM recovery partitions, or other recovery partitions used by other versions of Windows you've used on your PC).

    A normal installation in a UEFI system should be using 4 partitions:

    1. the "boot" partition: don't touch it, should be 128MB in size, and formatted with NTFS
    2. the MSR ("System") partition: at least 100MB. It is not mountable, hidden, and uses a very specific file system (not NTFS)
    3. the standard partition covering most of the rest of the disk (this will be your C: drive)
    4. the Windows recovery partition: at least 300MB, formatted in NTFS, then hidden so that Windows will not mount it in normal startup using special attributes (this partition is visible in the Windows Disk Manager, but you cannot mount it from there as the option is disabled, but it may be mounted from the command line using DISKPART as shown above)

    Your system may contain other partitions if you have multiboot enabled for another OS, or if your PC maker created its own OEM recovery partition (usually located at end of disk), and you've still not used the OSM tool that proposes you to backup it to a DVD (and then optionally drop that partition to reclaim its used space on your drive).

    In the File Explorer, the volume should be mounted and visible, you can navigate in it.

    When you'll no longer need this R: partition, unmount it in the Disk Manager (just remove the drive letter), or in DISKPART using

    (locate the volume number nof the mounted R: drive)

    There you'll find a folder named \Windows\Recovery containing a windows image named "Winre.wim" that you can inspect and mount to see its content (you can mount this .wim image in readonly mode using the DISM tool, into a temporary folder).

    Then look into its own \Windows folder (within the mounted images) and locate the file used to boot the recovery environment. Sometimes in the past, when your system was running over UEFI the file in the image to use was named "winload.efi" but now it is the same file as when botting over MBR: "winload.exe".


    I discovered that Windows 10 changed the way it booted (this has changed a few weeks after the initial commercial release of Windows 10 on 29 July 2015), and forgot to change the setting in the BCD store, so when booting the recovery during the boot-time installation (after copying files before the first reboot), the installer was correctly copying the new content of the recovery partition, but did NOT change the BCD entry, which was now referencing an inexisting "\Windows\winload.efi" file that has been deleted (no longer needed, "winload.exe" is the same now for both MBR and UEFI boot methods, it autodetects itself if it is starting up from MBR BIOS or UEFI bios).

    As the recovery can no longer be found, this caused the PC to hang at boot time, just after installing the new recovery environment in its partition as it could not start it using the BCD setting (which was not updated). The symtom was that the boot time installer was starting its "green screen" and then reached about 22%, and then the "rotating dots" were no longer rotating, the PC was completely frozen (you can wait for hours, it will not unblock itself), you had to press the RESET button and the PC would reboot, not in the recovery partition but from the existing windows partition in which the installer had installed a "windows rollback" boot program. So you would then see Windows rollback back all the started installation and reboot again to return to the unupdated Windows: Windows 10 would then need to be downloaded again (you can look into the "Windows.BT~\Panther" temporary folder where there are logs, one of the logs contained "Host OS not found, cannot resurrect Windows... " just before the PC hanged).

    Microsoft has just acknowledge that this was a bug in its installer (that was signaled more than one year ago, but still not diagnosed correctly). This bug seems to have been present also since several years with Windows 8 and 8.1. But it affects mostly the users that have been using a prerelease of windows 10 after upgrading from Windows 7: if Windows 10 blocks like this during the upgrade, it's very probably that the content of the BCD store is in fact incorrect

    You also need to make sure that your file systems are not corrupted: CHKDSK /F in administrator mode.

    And make sure that you've not left behing some old unused drivers (that are not upgradable but that may hang now when the Windows 10 Plug n Play system will attempt to activate them just to see if there's a device really behind: the windows 10 installer attempts to resurrect all drivers even if they are not used.

    Another tool I found can also be helpful (sorry it is on a website showing only Chinese , but use Google Translator, the tool itself is translated into several languages: including English, Russian, French, Spanish, as the website is extremely basic, automated translation works correctly and there's not ads everywhere to confuse you like on download.com!): The tool is named "DISM++" available on "www.chuyu.me" (original site, beware of rogue locations you may find in search engines)

    Use DISM++ to perform cleanup (just use the recommended options, options in red may be used but may be risky): it can also save gigabytes of junk storage space left behind. It will notably cleanup all unused drivers to keep only those that are active. It will also cleanup all old system snapshots (Windows 10 manages the system rollbacks differently). Don't worry: use it before installing Windows 10, as Windows 10 will still create a backup of your existing Windows version, but does not care at all about other system snapshots. Basically DISM++ instegrates everything that is possible with DISM, but in a much more intuitive interface (without the overly complex syntax of DISM), plus some other tools (such as installing/removing Windows features or components or predeploying other software in the image; it works on online and offline Windows images and can open .wim, and .esd files and convert them from .iso).

    But even if DISM++ can avoid many problems you would encounter during the upgrade (notably with old unused drivers), it also does not diagnose the BCD store problem. Microsoft tools do not diagnose this problem. the Microsoft support also is also not able to diagnose it, and there's no troubleshooter. I found the bug and the solution myself after long searches (nearly one year with this problem on one PC).

    DISM++ can be used (instead of DISM) to mount the Winre.wim image using its point-and-click interface: you'll need an empty folder used to temporarily create a local copy of its content (this mounted image may also be opened in "read-write mode", meaning that when you'll unmount that image, the content of that temporary folder will be reflected into the .wim file, but you should not use that, the recovery image is in fact a preconfigured WinPE instance).


    Note that if your system still does not have its own recovery partition, or the recovery partition is still not enabled, the "Winre.wim" file is still in the C:\Windows\Recovery directory, or in the ISO image of Windows 10 you've downloaded or on the installation DVD. But it can be mounted the same way in a new empty directory using DISM or DISM++.

    The fact of transferring the Recovery environment from the C:\Windows\Recovery to the recovery partition is performed during the "green screen" step of the installer at boot time (this is done between 20% and 22%, then this boot time installer will attempt to launch the recovery from there: this is where the error will occur, as it blindly uses the content of the BCD store to locate the file to launch in the winre.wim image, wherever it is.


    If you also failed to upgrade Windows 7 or Windows 8.1 to Windows 10 since the system reserved partition error cannot be updated, now try taking solutions introduced in this post. If our solutions are proved to be useful for you, can you please share it to help more users? Or if you have any other good idea, can you please share it with us. Much appreciate!