Windows Update Error 0x80070017 — Fix the CRC Error

What Does This Error Mean?

Windows Update error 0x80070017 is a CRC (Cyclic Redundancy Check) error. It means Windows downloaded or copied update files, but the data is corrupted — like getting a damaged package in the mail. This is usually caused by a bad internet connection, a failing hard drive, or corrupted Windows Update cache files.

Affected Models

Windows 10
Windows 11
Windows 8.1
Windows Server

Common Causes

The update files downloaded with errors due to an unstable internet connection
Your hard drive has bad sectors that corrupted the downloaded update files
The Windows Update cache folder contains old, corrupted data
RAM errors are causing data to be written incorrectly during the update process
Disk space is critically low, causing the update files to be written incompletely

How to Fix It

Clear the Windows Update cache. Open Command Prompt as Administrator and run these commands one at a time: net stop wuauserv — then: ren C:\Windows\SoftwareDistribution SoftwareDistribution.old — then: net start wuauserv

This forces Windows to create a fresh cache folder and re-download the update from scratch. This fixes the error in most cases.
Run the Windows Update Troubleshooter. Go to Settings > System > Troubleshoot > Other troubleshooters and click Run next to Windows Update.

This built-in tool automatically detects and fixes many common update problems, including stuck cache files.
Run Check Disk to look for hard drive errors. Open Command Prompt as Administrator and type: chkdsk C: /f /r — type Y and restart.

This scan runs before Windows starts and checks your entire drive for bad sectors. It can take 1 to 3 hours but is worth running if other steps fail.
Run the System File Checker. Open Command Prompt as Administrator and type: sfc /scannow

Corrupted Windows system files can interfere with the update process. This tool finds and repairs them automatically.
Check available disk space. Open File Explorer, right-click your C: drive, and choose Properties. Windows Update needs several GB of free space. Delete temporary files using Disk Cleanup if space is low.

Insufficient disk space is a common but overlooked cause of this error. You need at least 10 to 20 GB free for major updates.

When to Call a Professional

If the error persists after clearing the update cache and running Check Disk, your hard drive may be failing. A technician can run a full drive diagnostic. If bad sectors are found across multiple areas, the drive should be replaced before it fails completely.

Frequently Asked Questions

What is a CRC error?

CRC stands for Cyclic Redundancy Check. It is a method of verifying that data was copied or downloaded without any corruption. Every file has a unique CRC 'fingerprint.' If the fingerprint of the downloaded file does not match what it should be, Windows knows the file is damaged and refuses to use it.

Will clearing the update cache delete my files?

No. The Windows Update cache (the SoftwareDistribution folder) only contains temporary update files that Windows downloaded. Deleting or renaming it does not affect your personal files, installed programs, or Windows settings. Windows will simply re-download the update files fresh.

Can a bad USB drive cause this error?

Yes, if you are installing a Windows update from a USB drive rather than downloading it. A corrupted or failing USB drive will produce CRC errors as Windows reads the files. Try creating a new installation USB using the official Microsoft Media Creation Tool and a different, known-good USB drive.