Medium Operating Systems ✓ Solution Verified by Community (100+ upvotes)

How to fix error 0x80070643 in Windows Update

MSI installer fatal error during installation. .NET Framework or Visual C++ runtime issue.

✅ 85% success rate
👥 100+ users verified
📅 Updated: 2026-08-12
⏱️ 30 min read
Source: Community Report · How we verify fixes
Error Code0x80070643
Affected SystemWindows Update (Microsoft)
DifficultyMedium
Estimated Time30 min
Requires Admin Rights⚠️ Yes
Requires Reboot🔄 Yes

Solution Steps

  1. 1 Open Command Prompt as Administrator.
  2. 2 Run DISM: DISM /Online /Cleanup-Image /RestoreHealth.
  3. 3 Run SFC: sfc /scannow.
  4. 4 Re-register Windows Installer: msiexec /unreg then msiexec /regserver.
  5. 5 Download and run .NET Framework Repair Tool from Microsoft.
  6. 6 If error is from a specific KB update: manually download and install from Microsoft Update Catalog.
  7. 7 Reset Windows Update components using Microsoft WUReset script.

Alternative Solutions

Method 2 (6 upvotes)

  1. Make sure the downloaded files are proper, try re-downloading them by backing up and removing C:\Windows\SoftwareDistribution\Download Note that you might need to stop and start Windows Search for this to work.
  2. Your WindowsUpdate.log contains: Windows failed to install the following update with error 0x80070643: ... When searching this error online, I found suggestions here that you could try: http://support.microsoft.com/kb/976982 (MSI FixIt and .NET re-installion)

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