Moderate Severity
0x80070643 Error: Windows Update Installation Failure
Error 0x80070643 indicates that a Windows Update or software installation has failed. This is commonly seen when installing .NET Framework updates, Windows Defender definition updates, or Microsoft Office updates. The error points to a problem with the Windows Installer service or corrupted installation data.
Common Causes
- .NET Framework installation is corrupted
- Windows Installer service is not running
- Corrupted Windows Update cache
- Conflicting software installation in progress
- Damaged Microsoft Security Essentials or Defender files
- Previous update partially installed
- MSI installer database corruption
Symptoms
- Windows Update shows installation failed
- Security definition updates fail repeatedly
- .NET Framework updates will not install
- Office updates fail to complete
- Error appears in Windows Update history
- Multiple updates may fail simultaneously
How to Fix 0x80070643
- Restart the Windows Installer service
- Run the .NET Framework Repair Tool
- Clear the Windows Update cache (SoftwareDistribution folder)
- Run DISM /Online /Cleanup-Image /RestoreHealth
- Manually install the failed update from Microsoft Update Catalog
- Repair or reinstall .NET Framework
- Run Windows Update Troubleshooter
What Is Error
Error code 0x80070643 is a Windows HRESULT error code that translates to "Windows Update Installation Failure". HRESULT codes are hexadecimal values used throughout the Windows operating system to indicate specific error conditions. When you see this error, it means Windows or an application encountered the condition described above and could not continue the operation.
The error code format breaks down as follows: the leading 0x8 indicates a failure, the next digits identify the facility (the Windows subsystem that generated the error), and the remaining digits specify the exact error condition.
How Serious Is
Error 0x80070643 is not typically an emergency, but it will prevent certain operations from completing. You can continue using your computer for other tasks while troubleshooting. Work through the fixes below in order, starting with the simplest solutions.