Solved: “we couldn't update the system reserved partition” Error

Theo Lucia

Jan 15, 2024 • Filed to: Windows Computer Solutions • Proven solutions

Once in awhile when installing a new operating system such as Windows 10, there will be issues encountered; a frequent one is an error prompt saying "We couldn't update system reserved partition". This can be resolved by following a series of commands to be put on your computer. One may also opt to rely on a third-party partition tool to make the task easier.

Overview of these problems

Installing, upgrading to, or updating Windows 7, 8, and 10 on a clean-formatted disk will create a partition on the disk at the beginning of the hard disk. This partition is the System Reserved Partition (SRP). The remaining unallocated disk will be used to create the system drive and install the operating system. An error may be encountered while updating the SRP. This could also appear as error code 0xc1900104, or error code 0x800f0922. This error due to the SRP being full. Third-party anti-virus and security software can fill this up. To resolve this, it should be first determined whether the SRP is GPT or MBR partition style.

To do this, the following steps should be done:

1. Press the Windows key + R. In the Run window that comes up, type diskmgmt.msc and press Enter.

2. Press-and-hold or right-click on the Disk (such as Disk 0) that contains the SRP, and select Properties.

3. Choose the Volumes tab.

4. The Partition Style: line will say either GUID Partition Table (GPT) or Master Boot Record (MBR)

According to the partition, choose your next step:

For Windows 10 with GPT partition:

1. Search for cmd. Press-and-hold or right-click on Command Prompt in the results, and select Run as administrator.

2. At the command prompt, type mountvol y: /s and then hit Enter. This will add the Y: drive letter to access the System Partition.

3. Type Y: and press Enter to switch to Y drive. Navigate Fonts folder by typing cd EFI\Microsoft\Boot\Fonts. Then type del *.* to delete font files.

For Windows 10 with MBR partition:

1. Press Win + R keys on the keyboard to open Run. In Run window, type diskmgmt.msc and press Enter to open Disk Management.

2. Select System Reserve by pressing and holding or right-clicking.

3. Select Change Drive Letter and Paths.

4. Choose Add.

5. Enter Y for the drive letter.

6. Tap or click OK.

7. In the Start menu, search for cmd. Fonts folder by typing cd Boot\Fonts.

9. Type takeown /d y /r /f . (include space and period after "f" for the command to work properly) then press Enter.

10. Back up the permission to the drive by typing the following and press Enter: icacls Y:\* /save %systemdrive%\NTFSp.txt /c /t

11. Type whoami and press Enter, and then record the user name. Type the following command and press Enter: icacls . /grant :F /t

12. Make sure you are still located in Fonts location (Y:\Boot\Fonts) as described in step 8. Then, Type del *.* to delete font files. The system may ask you if you are sure to continue, press Y and then enter to continue.

Restore permissions

1. Type the following command and press Enter: icacls Y:\ /restore %systemdrive%\NTFSp.txt /c /t

2. A message may display indicating some files failed while processing – this is normal as these files have been deleted after backing them up.

3. If the amount of successful files is none, then the command was executed incorrectly; you must have some files successfully processed before continuing.

4. Adjust the ACL back to the System by typing the following and press Enter: icacls . /grant system:f /t

5. Set the owner of the drive back to System by typing the following command and pressing Enter: icacls Y: /setowner "SYSTEM" /t /c

6. Go back to Disk Management and Refresh the data to confirm if the SRP now has a greater percentage of free space. If so, the drive letter can be removed at this point.

7. Right-click the System Reserved Partition.

8. Select Change Drive Letter and Paths.

9. Choose the Y: drive.

10. Select Remove.

11. Click OK.

Recommended third-party partition tool

Partitioning a drive in the steps listed above is complicated and requires advanced skill. It also gives the risk of losing data stored on the device. To make it easier, it is recommended to use a third-party partition tool like Minitool Partition Wizard. Programs like this are more reliable and powerful than Window's options. It claims to create/resize/format partition flexibly, convert disk between MBR and GPT disks, convert partition between NTFS and FAT32, and convert dynamic disk to basic without data loss.

Precautions should always be taken when attempting to resolve SRP issues. Make sure to always type in the prompts accurately and to always back up data before starting to partition disks. If still unsure of how to do this or want to complete the task easier, third-party partition tools may always be used.