0x80070643 🪟 Windows

Windows Error 0x80070643: Fatal error during installation

An MSI-based installer or update (often Defender definitions, .NET or the WinRE update KB5034441) failed during installation.

Seen on: Windows

Meaning

0x80070643 wraps MSI error 1603, a generic fatal installer failure. The detailed reason is in the installer’s log. A well-known case is the WinRE update failing because the recovery partition is too small.

Common causes

  • Corrupted .NET Framework installation
  • Recovery (WinRE) partition too small for the update
  • Previous install of the same product left behind
  • Antivirus or insufficient permissions during MSI install

⚡ Quick fix

  1. Run the .NET Framework Repair Tool
  2. For KB5034441, follow Microsoft’s guidance to resize the WinRE partition or hide the update
  3. Uninstall the older version first, then reinstall
  4. Install with logging to find the failing step

Detailed fix by platform

Windows

  1. Get a verbose MSI log:
    bat
    msiexec /i setup.msi /l*v "%TEMP%\install.log"
:: search the log for "Return value 3" — the lines above it show the failing action

How to diagnose

  1. Product — Which update or installer?
  2. MSI log — What action fails before "Return value 3"?
  3. Partition — For WinRE updates: recovery partition size?

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