Windows Update Error 0x80070780 — Fix Guide

What Does This Error Mean?

The 0x80070780 error means 'The file cannot be accessed by the system.' During the update process, Windows tried to read or write a file but was blocked — either because another program has the file locked, the file is on a failing drive sector, or the file is missing entirely. This error most commonly appears during large feature updates rather than routine monthly patches.

Affected Models

Windows 10
Windows 11

Common Causes

A running program has a Windows system file locked open and is preventing the update from replacing it
The Windows update cache contains a corrupted partial download that Windows cannot read correctly
Bad sectors on your hard drive or SSD are preventing proper read/write access to update files
Antivirus software is intercepting file access and blocking the update from writing files
The Windows temporary folder is full or contains corrupted files from a previous failed update attempt

How to Fix It

Restart your computer before trying the update again. A restart closes all open programs and releases any file locks that may be blocking the update.

Do a full restart — not Sleep or Hibernate. After restarting, go to Settings > Windows Update and try installing the update immediately, before opening other programs.
Temporarily disable your antivirus before running the update. Open your antivirus program, find the option to disable real-time protection, turn it off, run the update, then re-enable protection when done.

Antivirus programs can intercept file writes during updates and misidentify update activity as suspicious. Disabling it briefly while updating is safe, provided you re-enable it immediately afterward.
Clear the Windows Update download cache. Open Command Prompt as Administrator and run: net stop wuauserv — then delete the contents of C:\Windows\SoftwareDistribution\Download\ — then: net start wuauserv

This forces Windows Update to re-download the update files from scratch, eliminating any corrupted partial downloads that are causing access errors.
Run a disk check to look for bad sectors. Open Command Prompt as Administrator and type: chkdsk C: /f /r — type Y when asked to schedule it for next restart, then restart.

CHKDSK will scan your drive for bad sectors and file system errors. The /r flag attempts to recover data from bad sectors. This process takes 20 to 60 minutes during restart.
Run System File Checker followed by DISM. In Administrator Command Prompt: sfc /scannow — wait for completion — then: DISM /Online /Cleanup-Image /RestoreHealth — restart and retry the update.

These two tools together repair Windows system files and the update infrastructure. Running them in sequence is more thorough than running either one alone.

When to Call a Professional

If the drive passes CHKDSK but the error persists, consider using the Windows Media Creation Tool to upgrade directly. This bypasses the normal update mechanism entirely and can succeed when the standard updater cannot. For persistent disk-related errors, a technician can run manufacturer-specific drive diagnostics to determine whether the drive is failing.

Frequently Asked Questions

Why does this error happen more with big Windows updates?

Major Windows feature updates (like upgrading from Windows 10 21H2 to 22H2) replace thousands of files simultaneously. The more files that need to be replaced, the higher the chance that one of them is locked by a running program or sitting on a damaged disk sector. Routine monthly security patches only replace a handful of files and rarely run into this problem.

Will clearing the download cache delete anything important?

No. The SoftwareDistribution\Download folder only contains temporary files that Windows Update downloaded. These are not installed yet — they are just staged for installation. Deleting them is completely safe. Windows Update will simply re-download them on the next attempt. Your personal files, installed programs, and existing Windows settings are not affected.

How do I know if my hard drive is causing this error?

If CHKDSK finds and fixes bad sectors, the drive was likely causing the problem. After CHKDSK repairs the drive, retry the update — it will often succeed. If CHKDSK finds a large number of bad sectors, the drive is failing and should be replaced soon. You can also check drive health with the free tool CrystalDiskInfo — it reads S.M.A.R.T. data from your drive and shows its overall health status.