This document explains how to fix Microsoft Windows error 802040020 if it is not working properly or throwing an error while installing, updating or upgrading Windows.

The error message may look like:
– Windows could not search for new updates. An error occurred while checking for new updates for your computer.
– Some updates were not installed. Failed: 32 updates
Error(s) found: Code 802040020 Windows update encountered an unknown error.

This solutions applies for following version of Microsoft Windows:

  • Windows 7
  • Windows 8
  • Windows 8.1
  • Windows 10
Error 802040020 Windows Update Overview
Avg. Time to Resolve Issue   30 mins
Difficulty Very Hard
Log Name: MicrosofWindowsUpdateError6594.log
Source: Device-manager
Event ID: 7979
Operating System
  • Windows 7
  • Windows 8
  • Windows 8.1
  • Windows 10
Level: System Error
User: User
  • Faulting Application Name: Window Update Manager , version: 3.0.7205.30327, time stamp: 0×41117444
  • Faulting module name: Windows  event.dll, version: 1.6.6133.35958
  • Exception code: 0xc03b166a
  • Fault offset: 0xc07b239f
  • Faulting process ID: 0×550
  • Faulting application start time: 0x800a0a37064993
  • Faulting application path: ~<userpath>
  • Faulting module path: ~C:\Windows\System32
  • Report ID: g4b89g86-7754-45g8-8793-4852gcg3a969
Also Known as
  • WindowsUpdate_802040020
  • 802040020
  • WindowsUpdate_802040020e
  • 802040020e
  • 0x802040020
  • fehler code 802040020, foutcode 802040020, fejlkode 802040020, code d’erreur 802040020, codice di errore 802040020, feil kode 802040020, cod de eroare 802040020, código de error 802040020

Cause of 802040020 Windows Update Error Code

  • DNS Conflict
  • Junk files location is infected with active threat

Steps to resolve Windows Error 802040020

Step 1: Check Proxy Server Settings

1. In Start Searchbox type CMD
2. Click on CMD.
Office Resolve Error Proxy Check 3. In command Prompt Copy following commands (Simply select the command and press ctrl+c and press ctrl+v in command prompt)

 netsh winhttp import proxy source=ie 

Check Proxy Setting

Note: You will need Administrator Access to Run the above command. Simply Right Click on cmd button and select “Run as Administrator

If you get the message “Direct Access (no proxy server)“, continue to the next step otherwise disable proxy from Network Settings.

 You can contact our 24×7 Live support for any help during the whole process. 

Step 2: Disable Windows Firewall Temporarily

1. In Start Search box type Firewall.cpl
Open Windows Firewall2. Click on Windows Firewall.
3. Click on “Turn Windows Firewall On or Off
Turn Windows Firewall on or off4. In Private network Setting, select “Turn off Windows firewall (not recommended)
5. Do the same for Public Network Setting.
Disable Windows Firewall6. Press OK.
Note: After the issue is resolved you must turn the Windows Firewall on.

In most cases Microsoft Windows update error 802040020 should be resolved by following above steps. If however the issue still persists it means there is some critical issue with your system which needs to be fixed manually and is recommended to be done by an experienced Computer Technician.

You can chat one-on-one with one of our Microsoft Certified Support Representative 24/7 by clicking on the Chat button.

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Last Updated: 26/02/2016
Solution ID: 738234

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    April 13th, 2016

    Posted In: Microsoft Windows

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