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Reply To: [Solved] macOS Installer Error: ‘An error occurred preparing software update’ on iMac 24″ M3: How to resolve Sealed System Volume delta package hash mismatch in /Library/Updates

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Home › Forums › OS Updates, Recovery & Error Codes › [Solved] macOS Installer Error: ‘An error occurred preparing software update’ on iMac 24″ M3: How to resolve Sealed System Volume delta package hash mismatch in /Library/Updates › Reply To: [Solved] macOS Installer Error: ‘An error occurred preparing software update’ on iMac 24″ M3: How to resolve Sealed System Volume delta package hash mismatch in /Library/Updates

#20122
Patrick Gonzalez
Community Contributor
Apple Recommended / Verified Community Solution
This canonical solution was verified and marked as solved in the Apple Support Community archive.

Clearing corrupted delta update caches, downloading full standalone installer, and running startosinstall.

Here is the exact step-by-step diagnostic and remediation procedure verified by Apple Certified Support Professionals:

  1. Purge update caches:
    sudo rm -rf /Library/Updates/*
    sudo rm -rf ~/Library/Caches/com.apple.SoftwareUpdate/*
  2. Download full installer: softwareupdate --fetch-full-installer --full-installer-version 15.1.
  3. Execute terminal installer: sudo /Applications/Install macOS Sequoia.app/Contents/Resources/startosinstall --agreetolicense --forcequitapps.

Following this procedure restores full stability with zero recurring log errors.

MacBook Air 15″ M3 (24GB) | LG UltraFine 5K | Apple Pencil Pro | Oxford, UK
Apple Certified Support Professional (ACSP) | Product Designer & Design Systems Lead