Warning
Create a Time Machine backup before major updates, disk operations, or security changes on macOS.
What you will achieve
macOS upgrades fail silently when disk is full — free space the right way first.
1) Review biggest storage categories
Open System Settings → General → Storage and identify large files, iOS backups, and old installers.
2) Clean safely
- Empty Bin.
- Remove old Xcode derived data and stale downloads.
- Move large archives to external storage.
3) Confirm free space in Terminal
df -h /