Checking if the system drive has enough free space is a key step to resolve the problem of Windows update failure and rollback. If the C drive is insufficient, the update may not be completed, and 10-20GB is usually reserved. The response methods include: using disk cleaning to delete temporary files, uninstalling infrequently used programs, and automatically cleaning through the storage awareness function in the settings.

You're trying to install Windows updates, and then this pops up: "We couldn't complete the updates, Undoing changes." It's frustrating, especially if it keeps happening. The good news is, it's not always a major issue — just something blocking the update process.

Here are some of the most common causes and practical fixes you can try without jumping into advanced troubleshooting right away.

Check for Enough Free Space

One of the simplest but often overlooked reasons is not having enough free space on your system drive (usually C:). Windows needs room to download and apply updates.

• How much do you need? At least 10–20 GB free is usually safe.
• What to do:
  • Delete temporary files via Disk Cleanup
  • Uninstall unused programs
  • Use Storage Sense in Settings to automatically clean up

If you're running low, that could be why the update failed and rolled back.

Run the Windows Update Troubleshooter

Windows has a built-in troubleshooter that can catch and fix many common issues with updates.

• Go to Settings > System > Troubleshoot > Additional troubleshooters
• Find Windows Update in the list and click Run

It might detect problems like corrupted update components or service issues and attempt to fix them automatically.

Reset Windows Update Components Manually

If the troubleshooter doesn't help, resetting the update system manually can work. This basically clears out stuck downloads and resets the services that handle updates.

Here's what to do:

• Open Command Prompt as Administrator
• Run these commands one by one:

 net stop wuauserv
net stop cryptSvc
net stop bits
net stop msserver
ren C:We couldnt complete the updates, Undoing changes Windows fixWindowsWe couldnt complete the updates, Undoing changes Windows fixSoftwareDistribution SoftwareDistribution.old
ren C:We couldnt complete the updates, Undoing changes Windows fixWindowsWe couldnt complete the updates, Undoing changes Windows fixSystem32We couldnt complete the updates, Undoing changes Windows fixcatroot2 catroot2.old
net start wuauserv
net start cryptSvc
net start bits
net start msserver

After that, restart your PC and try checking for updates again.

Check for Corrupted System Files

Sometimes system files get damaged, and that can cause all sorts of issues, including failed updates.

Run this in an Admin Command Prompt:

 sfc /scannow

And after that finishes, also run:

 DISM /Online /Cleanup-Image /RestoreHealth

These scan and repair core Windows files. If they find anything broken, they'll try to fix it.

Getting the “Undoing changes” message isn't fun, but more often than not, one of these steps will clear it up. Start with the easiest ones — check disk space, run the troubleshooter — and move to the deeper fixes if needed.

Basically that's it.

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