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[Solved] Mac Studio M2 Ultra Time Machine Backup Hanging on ‘Preparing Backup’ (macOS Sonoma 14.7) – Verified Troubleshooting

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Home › Forums › MacBook, iMac & macOS Lab › [Solved] Mac Studio M2 Ultra Time Machine Backup Hanging on ‘Preparing Backup’ (macOS Sonoma 14.7) – Verified Troubleshooting

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  • November 15, 2026 at 4:55 am #19937
    Jennifer Romero
    Community Contributor
    Diagnostic Hardware Specs: Mac Studio M2 Ultra | OS Version: macOS Sonoma 14.7 | Archive Source: Apple Support Community #256003051

    I am running into a persistent issue on my Mac Studio M2 Ultra running macOS Sonoma 14.7.
    Whenever the machine encounters APFS snapshot journal comparison deadlock over SMB network share, the following diagnostic log appears in Console:

    backupd: [com.apple.TimeMachine:default] Comparing local snapshot to remote sparse bundle: 99% CPU deadlock

    I verified that hardware connections are intact and tested across different power sources. What is the verified diagnostic procedure to permanently eliminate this symptom?

    MacBook Pro 14″ M4 (24GB) | DJI Mic 2 | Anker Prime 27,650mAh Bank | Singapore
    Digital Nomad & Travel Filmmaker | "Verified Apple Discussions Archive"
    November 15, 2026 at 4:55 am #19938
    Kathleen Flores
    Community Contributor
    Apple Recommended / Verified Community Solution
    This canonical solution was verified and marked as solved in the Apple Support Community archive.

    Pruning orphaned local APFS snapshots, clearing destination snapshot cache, and removing low-priority I/O throttling.

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

    1. Stop backup daemon: sudo tmutil stopbackup && sudo killall -9 backupd.
    2. Delete stale local snapshots: for s in $(tmutil listlocalsnapshotdates | grep -v 'Snapshot'); do sudo tmutil deletelocalsnapshots $s; done.
    3. Disable CPU throttle during sync: sudo sysctl debug.lowpri_throttle_enabled=0.

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

    MacBook Pro 14″ M4 Pro (48GB) | iPhone 15 Pro | iPad Air M2 | Atlanta, GA
    Apple Certified Support Professional (ACSP) | iOS / Swift Engineer
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