How to Use WinDiff to Compare Registry Files

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Article ID: 171780 - View products that this article applies to.
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How can you compare registry entries before and after an upgrade, the installation of a new software package, or between two computers?


To use the Windows NT 3.51 or 4.0 Resource Kit utility Windiff.exe to compare the differences between the registry entries before and after an upgrade, perform the following:

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.
  1. Start Regedt32.exe.
  2. Select each registry root that you want to compare.

  3. From the menu bar, click Registry.
  4. Click Save Subtree As.
  5. Click Save as type.
  6. Select Text files.
  7. Save the file as Filename.old.
  8. Follow the above steps for all subtrees.
  9. Install the new software or perform the upgrade.
  10. After the upgrade or install repeat steps 2-6.
  11. Save the file as
  12. Run Windiff from the resource kit and compare the two files, filename.old and
NOTE: This procedure can be done for individual keys as well.


Article ID: 171780 - Last Review: October 31, 2006 - Revision: 1.1
  • Microsoft Windows NT Workstation 3.51
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 3.51
  • Microsoft Windows NT Server 4.0 Standard Edition
kbhowto KB171780

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