"We couldn't complete the updates, undoing changes" means Windows downloaded and started installing an update, hit an error, and rolled itself back to the previous state. Your PC is safe — nothing is broken — but the update didn't install.

Why This Happens

The most common causes are corrupted update cache files, a full or nearly-full system drive, a conflicting driver, or a damaged Windows component store. The good news: each of these is fixable.

Step 1: Check Your Free Disk Space

Open File Explorer and check how much space is free on your C: drive. Windows Updates need at least 10–20 GB of free space to install safely. If you're low, use Settings > System > Storage > Temporary files to clean up.

Step 2: Clear the Windows Update Cache

Stale or corrupted update files are the most common cause. Here's how to wipe them cleanly:

  1. Right-click the Start button and choose Terminal (Admin) or Command Prompt (Admin).
  2. Run these commands one at a time, pressing Enter after each:
net stop wuauserv
net stop bits
net stop cryptsvc
  1. Open File Explorer and navigate to C:\Windows\SoftwareDistribution\Download. Select all files inside and delete them. Do the same in C:\Windows\System32\catroot2.
  2. Restart those services:
net start wuauserv
net start bits
net start cryptsvc

Now go to Settings > Windows Update and try again.

Step 3: Repair the Component Store

In the same elevated terminal, run:

DISM /Online /Cleanup-Image /RestoreHealth

This can take 15–30 minutes. Don't close the window. When it finishes, run:

sfc /scannow

Restart your PC and attempt the update again.

Step 4: Run the Windows Update Troubleshooter

Go to Settings > System > Troubleshoot > Other troubleshooters and run the Windows Update troubleshooter. It can detect and fix issues that the manual steps above don't catch, such as incorrect service permissions.

Step 5: Install the Update Manually

If a specific update keeps failing, look up its KB number in Settings > Windows Update > Update history, then visit the Microsoft Update Catalog (search the KB number) to download and install it directly.