how to fix "We couldn't update the system reserved partition error"

Question

how to fix "We couldn't update the system reserved partition error"

chris spivey 5

how do I fix "We couldn't update the system reserved partition error"

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2 answers

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Answer 1

Ramesh 177.7K Volunteer Moderator

@Terry Smith:

Now, please run these commands:

mountvol Y: /s

cd /d Y:\EFI\Dell\bios\recovery

move BIOS_PRE.rcv C:\

dir Y:\

Post the output.

If 20 MB of disk space is freed up on the EFI partition, rerun the 25H2 setup.***

See also:

We couldn't update the system reserved partition Error when installing 24H2 on Windows 11 - Microsoft Q&A

Terry Smith 25 Reputation points

2025-11-01T14:27:25.2033333+00:00
Yes now exceeds 20mb

C:\Windows\System32>Y:\EFI\Dell\bios\recovery move BIOS_PRE.rcv C:\ dir Y:\

'Y:\EFI\Dell\bios\recovery' is not recognized as an internal or external command,

operable program or batch file.

C:\Windows\System32>mountvol Y: /s

The directory is not empty.

C:\Windows\System32>cd /d Y:\EFI\Dell\bios\recovery

Y:\EFI\Dell\Bios\Recovery>move BIOS_PRE.rcv C:\

1 file(s) moved.

Y:\EFI\Dell\Bios\Recovery>dir Y:\

Volume in drive Y has no label.

Volume Serial Number is 4C8B-B6BA

Directory of Y:\

09/11/2025 07:10 AM <DIR> EFI

0 File(s) 0 bytes 1 Dir(s) 32,627,712 bytes free

Y:\EFI\Dell\Bios\Recovery>C:\Windows\System32>Y:\EFI\Dell\bios\recovery move BIOS_PRE.rcv C:\ dir Y:\

'Y:\EFI\Dell\bios\recovery' is not recognized as an internal or external command,

operable program or batch file.

C:\Windows\System32>mountvol Y: /s

The directory is not empty.

C:\Windows\System32>cd /d Y:\EFI\Dell\bios\recovery

Y:\EFI\Dell\Bios\Recovery>move BIOS_PRE.rcv C:\

1 file(s) moved.

Y:\EFI\Dell\Bios\Recovery>dir Y:\

Volume in drive Y has no label.

Volume Serial Number is 4C8B-B6BA

Directory of Y:\

09/11/2025 07:10 AM <DIR> EFI

0 File(s) 0 bytes 1 Dir(s) 32,627,712 bytes free

Y:\EFI\Dell\Bios\Recovery>
Terry Smith 25 Reputation points

2025-11-01T14:28:15.0133333+00:00

Hi Ramesh...Now downloading update. I believe this is fixed. Thank you so much for your help. Microsoft support could not resolve.
Ramesh 177.7K Reputation points Volunteer Moderator

2025-11-01T14:28:43.5266667+00:00

Great, that should resolve the We couldn't update the system reserved partition error error.
Ramesh 177.7K Reputation points Volunteer Moderator

2025-11-01T14:29:03.1133333+00:00

You're most welcome, Terry.
Terry Smith 25 Reputation points

2026-02-28T10:52:01.21+00:00

Hi Ramesh,

I'm getting the error message "We couldn't update the system reserve partition" again when trying to use latest MS update. Can you reconfirm the procedure to fix?
Ramesh 177.7K Reputation points Volunteer Moderator

2026-02-28T10:53:53.2433333+00:00
Hi Terry,

Please open an admin Command Prompt window and run these commands one by one:

mountvol Y: /s del /q Y:\EFI\Microsoft\Boot\Fonts\*.ttf powershell -command "GCI Y:\ -File -Recurse | Sort Length -descending | Select FullName, Length, Mode -first 10" dir Y:\

Post the output here.
Terry Smith 25 Reputation points

2026-02-28T11:07:52.8166667+00:00

Hi Ramesh,

It's crazy. I updated per your instructions and it now downloads. Will I need to do this again in the future for this type of Insider Feature Review Update?

Thanks,

Terry
Ramesh 177.7K Reputation points Volunteer Moderator

2026-02-28T11:15:55.7166667+00:00

Hi Terry,

Will I need to do this again in the future for this type of Insider Feature Review Update?

Unfortunately, yes. You may need to do that for every feature update because the OEMs store the BIOS update images (which consumes most of the space) in the EFI partition.

A permanent fix will be to resize the EFI partition to 200 MB or more using AOMEI partition assistant (free). I'd suggest backing up your OS partition before modifying the disk layout.

References

Free Partition Manager for Windows PC-AOMEI Partition Assistant Standard

How to Resize the EFI System Partition in Windows
Terry Smith 25 Reputation points

2026-03-28T10:56:32.7033333+00:00

Hi Ramesh,

Now sure if you have knowledge on the latest Microsoft Oauth New Outlook issue which started earlier this month? Can use New Outlook any longer due to inability to establish authentication.
Ramesh 177.7K Reputation points Volunteer Moderator

2026-03-28T10:58:48.1066667+00:00

@Terry Smith

MSFT released an out-of-band update for that issue. March 21, 2026—KB5085516 (OS Builds 26200.8039 and 26100.8039) Out-of-band - Microsoft Support

Have you installed that?
Terry Smith 25 Reputation points

2026-03-28T11:06:15.3633333+00:00

No. Should I download and install this fix. Wonder why not released?
Ramesh 177.7K Reputation points Volunteer Moderator

2026-03-28T11:08:19.4033333+00:00

Please open Windows Update and check for updates. If the out-of-band update appears, install it.

To check your current OS build, run winver.exe.
Terry Smith 25 Reputation points

2026-03-28T11:20:31.8633333+00:00

Looks like the out-of-band update hasn't landed yet. I'm on version 25H2 (OS build 26220.8079)
Ramesh 177.7K Reputation points Volunteer Moderator

2026-03-28T11:34:42.2+00:00

Hi Terry,

OS build 26220.8079 is Windows Insider.

You may post this question in the Windows Insider forum.

Tag:"windows 11" in "Windows Insider Program" | Microsoft Community Hub
Terry Smith 25 Reputation points

2026-03-28T12:00:44.82+00:00

Thanks Ramesh...will do!
Chiran Nair 0 Reputation points

2026-06-08T21:47:46.24+00:00

Thanks. It worked.

Answer 2

Arlene D 36,095 Independent Advisor

Hi there! That error usually means your System Reserved Partition is too small for the update to install. Are you updating Windows 10 or Windows 11? The official Microsoft fix is to check your partition in Disk Management, and if it’s under 500 MB, you’ll need to free up space or extend it. You can do this by using the Windows installation media, selecting Repair your computer, opening Command Prompt, and delete unneeded language or font files. Once space is freed, try the update again.

Terry Smith 25 Reputation points

2025-11-01T13:36:57.03+00:00

Hi Arlene...How do I expand? My Disk 0 Healthy EFI system partition is 100mb.
Ramesh 177.7K Reputation points Volunteer Moderator

2025-11-01T13:56:02.38+00:00
Hi Terry,

We can free up the EFI partition by deleting the font files in that partition. Please open an admin Command Prompt window (instead of PowerShell) and run these commands one by one:

mountvol Y: /s del /q Y:\EFI\Microsoft\Boot\Fonts\*.ttf powershell -command "GCI Y:\ -File -Recurse | Sort Length -descending | Select FullName, Length, Mode -first 10" dir Y:\

Post the output here.
Terry Smith 25 Reputation points

2025-11-01T14:03:16.2833333+00:00
Hi Ramesh

The del /q Y:\EFI\Microsoft\Boot\Fonts*.ttf did not work.

Remove-Item : A positional parameter cannot be found that accepts argument

'Y:\EFI\Microsoft\Boot\Fonts*.ttf'.

At line:1 char:1

del /q Y:\EFI\Microsoft\Boot\Fonts*.ttf

+ CategoryInfo : InvalidArgument: (:) [Remove-Item], ParameterBindingException + FullyQualifiedErrorId : PositionalParameterNotFound,Microsoft.PowerShell.Commands.Remo veItemCommand

If possible, can you reconfirm?

Thx
Ramesh 177.7K Reputation points Volunteer Moderator

2025-11-01T14:05:30.3166667+00:00

Terry, All those commands must be run from Command Prompt admin, instead of PowerShell, as already mentioned.
Terry Smith 25 Reputation points

2025-11-01T14:09:33.35+00:00
Here is an update. Thx for reminding me.

C:\Windows\System32>mountvol Y: /s

The directory is not empty.

C:\Windows\System32>del /q Y:\EFI\Microsoft\Boot\Fonts*.ttf

Could Not Find Y:\EFI\Microsoft\Boot\Fonts*.ttf

C:\Windows\System32>powershell -command "GCI Y:\ -File -Recurse | Sort Length -descending | Select FullName, Length, Mode -first 10"

FullName Length Mode

Y:\EFI\Dell\Bios\Recovery\BIOS_CUR.RCV 18887831 -a----

Y:\EFI\Dell\Bios\Recovery\BIOS_PRE.rcv 18851216 -a----

Y:\EFI\Dell\SOS\Fonts\chs_boot.ttf 3696752 -a----

Y:\EFI\Dell\SOS\Fonts\cht_boot.ttf 3440640 -a----

Y:\EFI\Dell\SOS\bootmgfw.efi 2855368 -a----

Y:\EFI\Microsoft\Boot\bootmgfw.efi 2855368 -a----

Y:\EFI\Boot\bootx64.efi 2855368 -a----

Y:\EFI\Dell\SOS\bootmgr.efi 2837416 -a----

Y:\EFI\Microsoft\Boot\bootmgr.efi 2837416 -a----

Y:\EFI\Microsoft\Boot\memtest.efi 2604928 -a----

C:\Windows\System32>dir Y:\

Volume in drive Y has no label.

Volume Serial Number is 4C8B-B6BA

Directory of Y:\

09/11/2025 07:10 AM <DIR> EFI

0 File(s) 0 bytes 1 Dir(s) 13,775,872 bytes free

C:\Windows\System32>

Terry Smith 25

Hi Ramesh...Here are the results. Not sure if worked?

C:\Windows\System32>mountvol Y: /s cd /d

Creates, deletes, or lists a volume mount point.

MOUNTVOL [drive:]path VolumeName

MOUNTVOL [drive:]path /D

MOUNTVOL [drive:]path /L

MOUNTVOL [drive:]path /P

MOUNTVOL /R

MOUNTVOL /N

MOUNTVOL /E

MOUNTVOL drive: /S

path        Specifies the existing NTFS directory where the mount

            point will reside.

VolumeName  Specifies the volume name that is the target of the mount

            point.

/D          Removes the volume mount point from the specified directory.

/L          Lists the mounted volume name for the specified directory.

/P          Removes the volume mount point from the specified directory,

            dismounts the volume, and makes the volume not mountable.

            You can make the volume mountable again by creating a volume

            mount point.

/R          Removes volume mount point directories and registry settings

            for volumes that are no longer in the system.

/N          Disables automatic mounting of new volumes.

/E          Re-enables automatic mounting of new volumes.

/S          Mount the EFI System Partition on the given drive.

Possible values for VolumeName along with current mount points are:

\\?\Volume{f40429d7-82a6-4102-8bad-752aeb46c192}\

    C:\

\\?\Volume{ebc1ffa7-e5f7-4a47-bd5e-daa777ee28fd}\

    *** NO MOUNT POINTS ***

\\?\Volume{004fdbd5-34df-4ed0-72ea-f0bf2878574f}\

    *** NO MOUNT POINTS ***

\\?\Volume{fcd5be98-62eb-4439-9ac1-6b567e8743bb}\

    *** NO MOUNT POINTS ***

The EFI System Partition is mounted at Y:\

C:\Windows\System32>Y:\EFI\Dell\bios\recovery move BIOS_PRE.rcv C:\ dir Y:\

'Y:\EFI\Dell\bios\recovery' is not recognized as an internal or external command,

operable program or batch file.

Ramesh 177.7K Reputation points Volunteer Moderator

2025-11-01T14:20:22.95+00:00

No it didn't because you combined all the lines into one single command.
carlo schoonebeek 0 Reputation points

2026-01-09T06:59:51.4166667+00:00

Thanks very much! it worked. I tried everything - nothing helped till now :)

much appreciated, Carlo
Ramesh 177.7K Reputation points Volunteer Moderator

2026-01-09T07:01:08.0833333+00:00

You're welcome @carlo schoonebeek