Fixed: Windows 10 Couldn't Be Installed due to System Reserved Partition

June 19, 2017

You may receive Windows 10 couldn't be installed during upgrade from Windows 7/8. This error is caused by system reserved partition not enough space. Here will show you how to extend system reserved partition.

Why did it happen?

Some people have encountered the error Windows 10 couldn’t be installed along with the description that we couldn’t update the system reserved partition while upgrading to Windows 10 from Windows 8.1 or Windows 7with Get Windows 10 application or Windows creation tool. The System Reserve Partition (SRP) is a small partition where Windows boot information is stored, generally at the beginning of the hard drive. The SRP is about 100MB in Windows 7 and 200MB in Windows 8. When some applications have written data to the system reserved partition, resulting the system reserved partition full, then Windows upgrade program will fail to update the SRP. To solve this problem, you can free up more space on the SRP or extend the partition.

Failed Install

Free up space on system reserved partition

Since the SRP has no drive letter, you cannot see it in File Explorer. You can use Disk Management to assign a drive letter and then use Disk Cleanup to free up space.

1. Press Windows key + R to bring up the Run window. Then type “diskmgmt.msc” in the box and press Enter.

2. At the Disk Management screen, right click on the system reserved partition and select “Change Drive Letter and Paths”.

Change Drive Letter

3. At the next screen, choose “Add” and enter “Z” for the drive letter.

4. Click “OK”.

5. Type “disk cleanup” in the search box and select Disk Cleanup.

6. In the pop up Drive Selection window, select Z: drive and click “OK”.

7. Follow the instructions to complete the disk cleanup.

After that, there should be sufficient space on the SRP to upgrade to Windows 10. Be aware that you should change the drive letter to “None” before trying to upgrade to Windows 10. If Windows 10 couldn’t update system reserved partition after running Disk Cleanup, you can extend the SRP.

Extend system reserved partition

Disk Management is not available for extending SRP because it can only extend a partition when there is unallocated space behind it. In nearly all of the cases, system partition (C: drive) is right behind the SRP. Fortunately, you can use free partition software AOMEI Partition Assistant Standard to extend SRP without data loss. Here is how:

1. Download the freeware and run it.

2. Right-click on C: drive and select “Resize Partition”. If your fresh install Windows 10 on a blank disk, Windows will create a 500MB system reserved partition, so you only need a few hundred MBs of unallocated space.

Select Resize

3. Check the option “I need to move this partition”, and then drag the slider bar from left to right, so the unallocated space will be next to SRP. Click “OK”.

Shrink System Drive

4. Right click on the system reserved partition and select "Resize Partition". In the pop-out window, drag the slider bar rightward to extend SRP with the unallocated space.

Extend Partition

5. Then preview the partition layout, and if it is good to you, cick “Apply” to apply this operation.


Then you will be prompted to restart your computer and complete these operations under PreOS Mode. When it finishes, your computer will reboot and then you can upgrade to Windows 10. By the way, if you had partitioned your hard drive before installing Windows, you would have had no system reserved partition. Therefore, there is another solution to fix the Windows 10 couldn’t be installed problem, which is to merge the system reserved partition into C: drive. However, it is not safe and not confirmed by Microsoft. In addtion, you can also use Allocate Free Space with AOMEI Partition Assistant Professional Edtion to add space to system reserved partition from another partition on the same disk.