Problem

When trying to update my Windows 7 Home Premium 64-bit to Windows 10 the other day using Windows Update I got this error “Something went wrong” and “We couldn’t update the system reserved partition”.

After some searching it seems this is related to not enough disk space on update partition, needs to be 50MB (thanks for the informative error message Microsoft…)

Solution

Thanks to Mister_Kurtz who in this post describes a solution when upgrading Windows 8.1. I’m on Windows 7 and upgrading to Windows 10 RTM (Release to Manufacturing) but with some slight changes it worked for me. The trick is to free up 50MB space on the Data partition, which is used for the upgrade, by truncating the NTFS log to 5MB. The original post includes steps to delete language files but I did not have any such files on my computer.

These are the steps that worked for me:

  1. Your user need to have administrator rights (full access)
  2. Go in to Disk Management – Start button, in search box (or Win+R) type
    diskmgmt.msc
  3. On the same disk as your C: drive the first partition will be Data of size 100MB. Right click on the Data partition and select Change Drive Letters and Paths. Then click Add an choose Y: as drive letter (or any other that is available)
  4. Open a Admin Command Prompt – Start button, in search box and type
    cmd.exe

    Right click the cmd.exe program and choose ‘Run as Administrator’.

  5. In the Admin Command Prompt goto Y:
    Run these commands:

    takeown /f . /r /d y
    icacls . /grant administrators:F /t 
    attrib -h -s -r bootmgr
    chkdsk Y: /F /X /L:5000
  6. Output from chkdsk should tell you that you now have at least 50MB free space.
    Retry running the Windows 10 upgrade, i did not need to reboot.