Mac Time Machine Errors — Backup Disk Full, Verification Failed, Sparse Bundle

Overview

Fix specific Time Machine errors including backup disk full on network drives, sparse bundle corruption, verification failures, and incremental backup stuck.

Key Details

• Time Machine uses APFS snapshots for local backups and sparse bundles for network backups
• Network backups (NAS) use .sparsebundle disk images which can become corrupted
• Backup disk full errors occur when Time Machine cannot reclaim space from old backups
• Verification failures on network backups indicate sparse bundle corruption
• Large files changing frequently (VMs, databases) can cause backup performance issues

Common Causes

• Network backup sparse bundle corrupted from disconnection during backup
• Backup disk genuinely full with oldest backups already thinned
• NAS permissions changed preventing Time Machine from writing
• Very large files (VM disk images, databases) consuming excessive backup space
• macOS update changing Time Machine behavior or APFS snapshot handling

Steps

1. 1For backup disk full: Time Machine preferences > select disk > forget, then re-add (starts fresh)
2. 2For sparse bundle corruption: mount the .sparsebundle manually, run fsck_hfs on it from Terminal
3. 3Repair sparse bundle: hdiutil attach -nomount -noverify /path/to/backup.sparsebundle then fsck_hfs -drfy /dev/diskN
4. 4Exclude large frequently-changing files: Time Machine preferences > Options > exclude VM files, databases
5. 5For NAS backups: ensure SMB (not AFP) is used on macOS Ventura+ and NAS permissions are correct

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Frequently Asked Questions