Windows Update Error 0x80070070 — Fix Not Enough Disk Space

What Does This Error Mean?

Windows Update error 0x80070070 means your computer does not have enough free disk space to download and install the update. This is one of the simplest update errors to understand and fix. You just need to free up space on your C: drive.

Affected Models

Windows 10
Windows 11
Windows 8.1

Common Causes

Your C: drive is nearly full and does not have enough free space for the update files
The Windows Update cache from previous failed downloads is using up disk space
Old Windows installation files from a previous upgrade are taking up gigabytes of space
The Recycle Bin or Downloads folder has accumulated large files that were never deleted
Large temporary files from programs or Windows itself are consuming available disk space

How to Fix It

Check how much free space you have. Open File Explorer and right-click your C: drive > Properties. You need at least 10 GB free for most Windows Updates, and 20+ GB for feature updates.

If you have less than 5 GB free, Windows Update will struggle to run properly regardless of other settings.
Run Disk Cleanup. Search 'Disk Cleanup' in the Start menu, select your C: drive, and click 'Clean up system files.' Check all boxes, especially 'Windows Update Cleanup' and 'Previous Windows installations.'

Previous Windows installation files can take 10 to 20 GB. Removing them is safe once your current Windows version is working well.
Empty your Recycle Bin and clear your Downloads folder. Right-click the Recycle Bin on your desktop and choose 'Empty Recycle Bin.' Then open your Downloads folder and delete files you no longer need.

These two locations are often full of forgotten files that can be taking up gigabytes of space.
Use Storage Sense to automatically clean up files. Go to Settings > System > Storage > Storage Sense and turn it on. Click 'Run Storage Sense now' to get an immediate cleanup.

Storage Sense can also automatically delete files in the Recycle Bin and Downloads folder after a set number of days.
Move large files off your C: drive. If you have videos, photos, or documents, move them to an external drive or another partition to free up space on the system drive.

You can also use the 'This PC' view in File Explorer to see which folders are taking the most space and target them for cleanup.

When to Call a Professional

If your drive is genuinely full even after cleanup, you may need a larger drive. A technician can clone your existing drive to a larger one, keeping all your files and programs intact. For laptops, adding a second drive or replacing the existing one is a common and affordable upgrade.

Frequently Asked Questions

How much free space does Windows Update need?

Small security updates typically need 1 to 3 GB of free space. Monthly quality updates may need 5 to 8 GB. Major feature updates (like upgrading to a new Windows version) can need 20 GB or more. Keeping at least 15 GB free at all times is a good habit.

Is it safe to delete the old Windows installation folder?

Yes, once you are happy with your current Windows version and it has been running well for a few weeks. The Windows.old folder is there to let you roll back if something goes wrong. After 30 days, Windows deletes it automatically — or you can delete it sooner through Disk Cleanup.

Can I install Windows Updates on an external drive to save space?

No. Windows Updates must be installed on the drive where Windows is installed, typically C:. You cannot redirect the installation to an external drive. The only solution is to free up space on the C: drive or replace it with a larger one.