FULL AI ANALYSIS

macOS Spotlight Indexing Hangs at 0% After Enabling Time Machine Backups to SMB Share

Generated Oct 3, 2026, 12:35:03 AM

Analysis summary

Spotlight errors referencing file-probing failures and -36 I/O errors point to SMB-specific file metadata or permission semantics that mds cannot handle on the remote share, causing indexing to stall. Time Machine over SMB relies on specific server-side support (sparsebundle, proper SMB attributes); if the NAS exposes files with unusual attributes or inconsistent RFC-compliant behavior, mds may block. Safest recovery is to isolate indexing from backup share and verify SMB share compatibility.

Possible causes

SMB share exposes attributes or file system features (e.g., resource forks, Finder metadata, incompatible POSIX ACL handling) that break mds's file probing routines.

90%

Network instability or SMB signing/encryption settings cause intermittent I/O errors that make mds treat the share as unreliable and stall indexing.

75%

Time Machine sparsebundle creation or locking is interfering with Spotlight's ability to traverse the share, causing repeated probe failures.

60%

Keychain credential/permission mismatch results in occasional permission denials (-36) during probe operations.

25%

Suggested fixes

Diagnostic step 1

Temporarily remove the SMB Time Machine target from Spotlight indexing: open System Settings > Siri & Spotlight > Privacy (or use mdutil -i off <mountpoint>) so the SMB mount is excluded while monitoring whether local indexing resumes. This is reversible.

Diagnostic step 2

Check NAS SMB settings: ensure SMB3 is enforced, disable SMB signing temporarily for a test if supported (note security implications), and confirm Synology recommended Time Machine/Apple-specific settings are applied. Coordinate with NAS admin and revert after test.

Diagnostic step 3

Validate the sparsebundle on the NAS for Time Machine integrity using DSM's built-in tools (do not delete the bundle). Create a small test SMB share and attempt indexing against it to isolate NAS configuration vs client issues.

Diagnostic step 4

Collect Console logs for mds/mds_stores and SMB mount negotiation while reproducing the stall and, if available, test with a second Mac to determine whether the problem is client-specific. If the issue persists and appears SMB-server related, escalate to NAS vendor support providing logs and timestamps—do not delete backup data.

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