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.Net Framework Service Pack 1 won't install

Symptoms: Windows update shows .Net Framework Service Pack 1 update available, but fails to install it. This may also apply to other .Net Framework updates that fail to install.

Causes: A corruption in the .NET Framework installation or by an inconsistency on the MSI database state.


  1. Use .Net Cleanup Utility to remove all versions of .Net Framework.
  2. Restart the computer when Cleanup Utility finishes.
  3. Reinstall .Net Framework in the following order:
  4. Restart the computer again
  5. Run Windows update, download and install any updates that may be available.

Note: This process will take up to 45 minutes to complete.

page | by Dr. Radut