1
Verify the likely cause
Remove the stale in-progress bundle, run tmutil thinlocalsnapshots and reconnect the Time Machine destination.
FULL AI ANALYSIS
Time Machine remains on Preparing backup indefinitely
Generated Sep 6, 2026, 11:54:26 PM
Analysis summary
The reported behaviour is consistent with a stale in-progress snapshot or damaged backup state prevents a new incremental scan. The safest next step is to verify that hypothesis with a reversible test before making permanent configuration changes.
Possible causes
A stale in-progress snapshot or damaged backup state prevents a new incremental scan.
80%A recent software, firmware or configuration change is exposing an existing compatibility issue.
36%Suggested fixes
2
Validate and monitor
Reproduce the issue once after the change, review relevant logs or metrics, and keep a rollback path until the system has remained stable.