How to Extend EFI System Partition (aka "System Reserved Partition") on Windows 11/10.
This guide contains step-by-step instructions on how to expand the size of the EFI system partition in Windows 11/10.
The EFI (Extensible Firmware Interface) System Partition (ESP) on UEFI systems, or System Reserved Partition (SRP) on MBR systems, is a small partition in Windows (~100MB) that is automatically created during Windows installation and contains the necessary Boot Configuration Data (BCD) to start Windows.
However, in some cases, especially when trying to update/upgrade Windows 11 to a newer version (eg. to version 24H2), the size of the EFI system partition is not sufficient to update the boot files, causing the Windows 11 Setup error "We couldn’t update system reserved partition" with error codes 0x800f0922 or 0xc1900201.
Since the Windows Disk Management tool does not allow extending the EFI system partition, in this tutorial I will show you how to resize the EFI System partition (aka "System Reserved Partition"), using a free partition management utility like "AOMEI Partition Assistant".
How to Resize the EFI System Partition using AOMEI Partition Assistant.*
ATTENTION: Follow the instructions below carefully and at your own risk, and as a precaution, back up all your important files to an external USB storage device before proceeding further.
Step 1. Install AOMEI Partition Assistant (FREE)
1. Download the freeware version of AOMEI Partition Assistant Standard.
2. When the download is completed double-click at the downloaded file to start the installation.
3. At the next screen click Skip and then click Install Now to install the free edition of AOMEI Partition Assistant Standard.
Step 2. Increase EFI System Partition size with AOMEI Partition Assistant.*
* ATTENTION: Follow the instructions below carefully and at your own risk, and as a precaution, back up all your important files to an external USB storage device before proceeding further.
To increase the size of the EFI System Partition (aka "System Reserved Partition"):
1. Open AOMEI Partition Assistant.
2. Select the drive C: and click Resize/Move Partition from the sidebar on the right.
3. On the next screen, select the option I need to move this partition and then click on the two arrows next to 'Partition size'.
4. Now, click the Down arrow next to the "Partition Size" field to reduce the size of the main C: drive by ~200 MB and assign this space to "Unallocated space after" field as in screenshot below.
5. Then, click and hold your mouse on the C: drive space and drag your mouse to the right, until all the allocated space goes from the "Unallocated space after" to the "Unallocated space before" field as in screenshot below. When done, click OK.
6. At this point, an Unallocated space should have been created between the Microsoft Reserved Partition and the C: drive, as in screenshot below. If so, continue to the next step, otherwise close AOMEI Partition Assistant without applying changes and start from scratch.
7. Now, select the Microsoft Reserved Partition and click Resize/Move Partition.
8. Click on the "16.00MB" square and, holding down the left mouse button, drag the square all the way to the right.
9. When done, click OK
10. At this point, the Unallocated space should have moved between the FAT32 – EFI System Partition and the Microsoft Reserved partition, as in the screenshot below.
![image_thumb[21]](https://www.wintips.org/wp-content/uploads/2025/04/image_thumb21.png "image_thumb[21]")
11. Now select the FAT32 – EFI System Partition and click Resize/Move Partition.
![image_thumb[22]](https://www.wintips.org/wp-content/uploads/2025/04/image_thumb22.png "image_thumb[22]")
12. Now click on the right side of the rectangle, then hold down the left button and drag the slider all the way to the right to select all the available capacity.
![image_thumb[23]](https://www.wintips.org/wp-content/uploads/2025/04/image_thumb23.png "image_thumb[23]")
13. When done, click OK.
![image_thumb[24]](https://www.wintips.org/wp-content/uploads/2025/04/image_thumb24.png "image_thumb[24]")
14. At this point, the FAT32 – EFI system partition will have "grown" by about 200 MB. Click Apply to apply the change.
![image_thumb[25]](https://www.wintips.org/wp-content/uploads/2025/04/image_thumb25.png "image_thumb[25]")
15. Then press Proceed on "Pending Operations" window to continue.
![image_thumb[26]](https://www.wintips.org/wp-content/uploads/2025/04/image_thumb26.png "image_thumb[26]")
16. Finally, click OK to Restart into PreOS mode.
![image_thumb[30]](https://www.wintips.org/wp-content/uploads/2025/04/image_thumb30.png "image_thumb[30]")
17. After the restart, you will see a DOS window showing the changes that AOMEI Partition Assistant is applying, and once this happens the computer will restart once more to apply all the changes. Once this done, the computer will boot normally into Windows.
18. After entering Windows, open AOMEI Partition Assistant again to verify that the size of the EFI system partition has been increased, and you're done!
![image_thumb[29]](https://www.wintips.org/wp-content/uploads/2025/04/image_thumb29.png "image_thumb[29]")
That's it! Let me know if this guide has helped you by leaving your comment about your experience. Please like and share this guide to help others.
Frequently Asked Questions
What is the EFI System Partition and why is it important?
The EFI (Extensible Firmware Interface) System Partition (ESP) is a small partition, about 100MB, created during Windows installation on UEFI systems. It contains the necessary Boot Configuration Data (BCD) to start Windows. It is crucial for booting up your Windows system.
Why might I need to resize the EFI System Partition?
You may need to resize the EFI System Partition if it is not large enough to accommodate updates or upgrades, such as when updating Windows 11 to a newer version, which can cause errors like 'We couldn’t update system reserved partition' with codes 0x800f0922 or 0xc1900201.
Can I resize the EFI System Partition using Windows Disk Management?
No, the Windows Disk Management tool does not allow extending the EFI System Partition. You will need a partition management utility, such as AOMEI Partition Assistant, to resize the partition.
Is there a risk involved in resizing the EFI System Partition?
Yes, resizing the partition involves a certain level of risk. It is advised to follow the instructions carefully and back up all important files to an external USB storage device before proceeding with the changes.
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October 26, 2025 @ 3:29 pm
Thank you so much for this. I have done it before but this seems to be the only page out there which explains it so simply and clearly.
I find it almost unbelievable that:
– Microsoft completely ignores that this is a problem WHICH THEY CREATED (this is my third time dealing with this (since Win11 is not updating from 23H2 to 24H2 or 25H2) – it happened twice before on my Win10 desktop (first time I ended up reinstalling Windows, last time I managed to repartition things as this page describes)
– Microsoft puts out an update/setup system which doesn't deal with this problem itself (isn't this exactly the kind of thing AN OPERATING SYSTEM is supposed to handle?!?)
– Microsoft don't even have a tool to do it
– there is almost nothing about this problem online (I went through so many incorrect "fixes" by following online advice the first time that I completely crashed the Win10 installation and had to reinstall)
July 15, 2025 @ 5:03 pm
It worked perfectly on my laptop with Windows 11 Home! Thank you very much!