Windows does not boot after compressing System Drive

We have seen how we can compress files, folders or even drives to save some disk space. To many compressing the System Drive or the C drive to save some more space may look tempting. But this can create problems!

Compressed System Drive – Windows will not boot

Using the Compress feature on the system drive can compress some of the files required to boot the Windows OS. This could simply make your Windows computer NOT boot! You could even end up with a boot-loop!

In this article, I’ll show you what you can do if your Windows computer fails to boot or goes into a boot-loop after compressing the system drive OS drive.

There are a couple of methods we can try. I’ll list all of them you can find the best method that works for you.

Run Startup Repair

The first method is to run the Startup Repair. It may or may not work, but it’s the easiest method to try. Run the Startup Repair, three different times. Because sometimes it sometimes takes three runs to fix it. If this does not fix your problem move on to the next option.

Manually uncompress the files

The next method is to manually uncompress the files of the Windows installation drive. Follow these steps:

  • Insert the Windows installation disc or USB flash drive, or a system repair disc, and then shut down your computer.
  • Then restart your Computer
  • When prompted, press any key, and then follow the instructions that appear
  • On the Install Windows page, or on the System Recovery Options page, choose your language and other preferences, and then click Next.

1 400x300 Fix: Unable to boot the System with error code 0x490, with Windows Startup Repair

  • Click Repair your computer.
  • Select the Windows installation you want to repair, and then click Next.

2 400x308 Fix: Unable to boot the System with error code 0x490, with Windows Startup Repair

  • Now click on “Load Drivers.”
  • You’ll get this screen. Click OK.


  • Now you’ll get an explorer window. Click on Computer


  • Right-click on Installation Drive which would be the C drive in most cases. Select Properties.


  • Uncheck on “Compress this drive to save disk space” and click Apply/OK.


  • Make sure it says “uncompress” and ensure that “Apply changes to drive C:\, subfolders and files” is selected.
  • Now click “OK” and wait for few minutes until it uncompresses.
  • Once it’s done reboot your computer normally and see if it loads.

This should work. If it does – great! If not, you have just one last chance!

Manually rebuild the MBR

The last method is to manually rebuild the MBR or Master Boot Record. There are a lot of ways to do that. You can follow this video tutorial created by me on how to Rebuild MBR. For details on this, check this tutorial on how to fix the Bootmgr is Missing issue.

Hope something helps! If none of the steps work, then feel free to post it in our forums. We’ll be glad to assist you there.

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Shyam aka “Captain Jack” is a Microsoft MVP alumnus and a Windows Enthusiast with an interest in Advanced Windows troubleshooting. Suggestions made and opinions expressed by him here are his personal one's and not of his current employers. He blogs at