This document explains how to fix Microsoft Windows error code C8000643 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: 55 updates
Error(s) found: Code C8000643 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 C8000643 Windows Update Overview
Avg. Time to Resolve Issue   40 mins
Difficulty Critical
Log Name: MicrosofWindowsUpdateError7742.log
Source: Device
Event ID: 4490
Operating System
  • Windows 7
  • Windows 8
  • Windows 8.1
  • Windows 10
Level: System Error
User: Admin
  • Faulting Application Name: Window Update Manager , version: 7.2.6703.12721, time stamp: 0×50552635
  • Faulting module name: Windows  update.dll, version: 5.3.0525.92090
  • Exception code: 0xa07g123d
  • Fault offset: 0xe08f377g
  • Faulting process ID: 0×754
  • Faulting application start time: 0x800c2b66090148
  • Faulting application path: ~<userpath>
  • Faulting module path: ~C:\Windows\System32
  • Report ID: g8e14e49-1235-33d5-9885-5755ebe5c237
Also Known as
  • WindowsUpdate_c8000643
  • C8000643
  • WindowsUpdate_C8000643e
  • C8000643e
  • 0xC8000643
  • fehler code C8000643, foutcode C8000643, fejlkode C8000643, code d’erreur C8000643, codice di errore C8000643, feil kode C8000643, cod de eroare C8000643, código de error C8000643

Cause of C8000643 Windows Update Error Code

  • Internet connectivity issue
  • Junk files location is infected with active malware

How to Resolve Windows Error Code C8000643

Step 1: Disable Windows Firewall Temporarily
1. Press Win Key + R and Type “Firewall.cpl” (without quotes)
2. Click OK.

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.

Step 2: Check for system corruption

1. Press Win Key + R and Enter “CMD” (without quotes)
2. Click OK.
open command prompt3. In command Prompt Copy following commands (Simply select the command and press Ctrl+C and press Ctrl+V in command prompt)

 sfc /scannow 

sfc scannow
The system will take some time to check. Let it run for a while. If it finds any issues in “os” integrity it will automatically fix it.

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

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

In most cases Microsoft Windows update error code C8000643 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: 07/02/2016
Solution ID: 786664

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    April 13th, 2016

    Posted In: Microsoft Windows

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