[Alan Adams]

Apple Recommended / Verified Community Solution

This canonical solution was verified and marked as solved in the Apple Support Community archive.

Flushing local keychain daemon caches and re-authenticating with primary device lock screen passcode.

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

1. Confirm saved passwords exist locally on your iPhone in Settings > Passwords.
2. On Mac, turn Passwords & Keychain OFF in iCloud settings.
3. Purge local keychain cache: rm -rf ~/Library/Keychains/*/ && sudo killall -9 securityd secd.
4. Re-enable Keychain in iCloud settings and verify identity with iPhone lock screen passcode.

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

MacBook Pro 14″ M1 Pro (16GB) | Apple Diagnostics Suite | Wi-Fi 6E Sniffer | Auckland, NZ

Apple Certified Support Professional (ACSP) | Apple Certified Service Technician (ACiT / ACSP)

[Alan Adams]

Apple Recommended / Verified Community Solution

This canonical solution was verified and marked as solved in the Apple Support Community archive.

Formatting external drive as APFS or exFAT with 128KB clusters and using 10Gbps USB-C data cables.

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

1. Format the external SSD on a Mac as APFS for optimal sequential write consistency.
2. Ensure cable is rated for 10Gbps or 20Gbps (USB 3.2 Gen 2×2); in-box white charging cables are USB 2.0 (40MB/s).
3. Use drives with sustained non-SLC cache write capabilities (e.g. SanDisk Extreme Pro v2 or Crucial T700 enclosures).

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

MacBook Pro 14″ M1 Pro (16GB) | Apple Diagnostics Suite | Wi-Fi 6E Sniffer | Auckland, NZ

Apple Certified Support Professional (ACSP) | Apple Certified Service Technician (ACiT / ACSP)

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