Reply To: [Solved] MacBook Pro 14″ M3 macOS Installer Error: ‘An error occurred preparing software update’ (macOS Sonoma 14.6) – Verified Troubleshooting

[Zachary Medina]

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.

Mac mini M2 Pro (32GB) | Dell UltraSharp U3223QE | Jamf Cloud Admin | Rotterdam, NL

Apple Certified Support Professional (ACSP) | Enterprise Mac Sysadmin & Jamf Pro Architect