Windows Update Error 0x800703E6 — Fix Guide

What Does This Error Mean?

Windows Update error 0x800703E6 means the update process was blocked — usually because an invalid memory address was accessed during the update. This translates to an 'Invalid Access to Memory Location' error deep inside Windows. It most often happens because of a corrupted Windows Update component, a conflicting security program, or damaged system files.

Affected Models

Windows 10
Windows 11
Windows Server 2019
Windows Server 2022

Common Causes

The Windows Update cache and component store have become corrupted, causing update downloads to fail
A third-party antivirus or security program is interfering with the Windows Update process
Windows Update service dependencies are stopped or set to manual when they should run automatically
Core Windows DLL files referenced during the update process have become corrupted
Insufficient disk space on the C: drive for the update to extract and install its files

How to Fix It

Run the Windows Update Troubleshooter first. Go to Settings > System > Troubleshoot > Other Troubleshooters > Windows Update, and click Run.

This automated tool finds and fixes the most common Windows Update problems. It is always worth trying before manual steps.
Reset the Windows Update components manually. Open Command Prompt as Administrator and run these commands one at a time: net stop wuauserv — net stop cryptSvc — net stop bits — net stop msiserver

This stops the four Windows Update services. Do not close Command Prompt yet — you have more steps to run.
In the same Command Prompt, rename the corrupted update folders: ren C:\Windows\SoftwareDistribution SoftwareDistribution.old — then: ren C:\Windows\System32\catroot2 catroot2.old

Renaming instead of deleting is safer. Windows will create fresh folders automatically when the services restart.
Restart the Windows Update services: net start wuauserv — net start cryptSvc — net start bits — net start msiserver — then restart your computer and try the update again.

This forces Windows Update to start completely fresh with a clean cache.
Temporarily disable your third-party antivirus software and try the update again. If it succeeds, your antivirus was blocking it. Add Windows Update to its exclusions list.

Remember to re-enable your antivirus immediately after the update finishes.

When to Call a Professional

If resetting Windows Update components and running system repairs do not clear this error, a technician can perform a more thorough repair. Persistent 0x800703E6 errors on a server environment may require a full component store rebuild. For business computers, your IT department should handle this to avoid unintended changes.

Frequently Asked Questions

Is it safe to rename the SoftwareDistribution folder?

Yes, it is completely safe. The SoftwareDistribution folder only holds temporary update download files. Renaming it forces Windows Update to create a fresh empty folder and re-download update files from scratch. Your personal files, programs, and Windows itself are not affected.

How much free disk space does Windows Update need?

Feature updates (like going from Windows 10 21H2 to 22H2) can require 10 to 20 GB of free space. Smaller security and quality updates typically need 1 to 5 GB. If your C: drive has less than 10 GB free, clear up space before trying to update — use Disk Cleanup to remove old files safely.

Will skipping this update cause security problems?

It depends on the update. Security patches are important and should not be skipped for long. Feature updates can usually wait a few weeks while you troubleshoot. Microsoft's Security Update Guide at microsoft.com describes how critical each update is.