I'm trying to install Windows 7 Ultimate over my existing Windows 7 Professional. I downloaded the ISO from Microsoft and burned the install disc at the slowest speed possible (x3).

I booted to the DVD, but at the second screen I am already getting an error! That screen I am choosing between "Upgrade" and "Custom". I am trying to choose "Custom" but then I get the error:

Windows installation encountered an unexpected error. Verify that the installation sources are accessible, and restart the installation.

Error code: 0xE0000100


There could be 3 reasons for this error:

  1. Partition problem described in KB939727
  2. Problem with the media or the bad iso/Win 7 installation (burn using another device or using another software; don't use RW media). Use the genuine Windows 7 Ultimate
  3. You can try the following:

    • Boot into Windows 7 installer DVD
    • Select Repair your computer
    • Select the Command prompt in the Choose the recovery tool dialog
    • Type diskpart
    • Press Enter
    • Type list disk
    • Press Enter
    • Identify the number of your target HD
    • Type select disk 0 (assuming that your disk is 0)
    • Press Enter
    • Type clean
    • Press Enter
    • Type exit

Now your MBR is cleaned up and you should be able to install the Windows 7

  • 1
    Thank God! Been screwing around with a RAID0 install on M.2 NVME (Samsung 970 Pro's) for 2 hours and this fixed it. – cchamberlain Jun 12 '19 at 10:28
  • That first link is now broken – Tom Sep 30 '20 at 18:18

This error is often caused by issues with the hard disk, especially the MBR. There are a couple things you can try. I would first try running a chkdsk and have it repair/recover any errors it finds. If that doesn't fix it, check for invalid disk partitions. You may need a tool like Parted Magic to fix issues with invalid partitions.


According to Error message when you use Windows Vista Setup to try to create a partition: "Error code: 0xE0000100":

Consider the following scenario. You have a Windows Vista-based computer. An image that the manufacturer created was used to install Windows Vista. The manufacturer used the System Preparation (Sysprep) tool to create this image. The computer's hard disk drive is partitioned into two or more partitions. The partition on which Windows Vista is installed is larger than 40 gigabytes (GB). Additionally, the size of the partition is a multiple of 4 GB. You run Windows Vista Setup. You delete the existing partition on which Windows Vista is installed. You try to create a new partition. In this scenario, you may receive an error message that resembles the following:

Even though the article is about an issue with Vista, additional searches revealed that the error code is usually related to a partitioning issue.

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