How to fix error: unable to unlink: Read-only file system (Time Machine snapshot) in Git

First, check if Time Machine is currently running a backup. An in-progress backup may be holding locks on files.

Check backup status from menu bar:
1. Click the Time Machine icon in the menu bar
2. Look for "Backing Up..." or a progress indicator
3. If a backup is running, wait for it to complete

Check via terminal:

# Check if Time Machine backup is in progress
tmutil status

If a backup is running, you can either:
- Wait for it to complete (recommended)
- Stop the backup (if urgent): tmutil stopbackup

After the backup completes, retry your Git operation - it may work without further action.

View all local snapshots on your Mac to understand what's holding the files:

# List all local snapshots
tmutil listlocalsnapshots /

# You'll see output like:
# com.apple.TimeMachine.2024-01-15-093042.local
# com.apple.TimeMachine.2024-01-15-120000.local
# com.apple.TimeMachine.2024-01-16-093042.local

Local snapshots are named with timestamps. Recent snapshots (within the last few hours or days) are normal. If you have many old snapshots, they may be accumulating because:
- Your backup drive hasn't been connected
- Time Machine is paused
- Disk space issues are affecting cleanup

Note the timestamps - you'll need them if you decide to delete specific snapshots.

Remove old local snapshots to release the file locks. Only delete snapshots you no longer need - they provide rollback capability even without your backup drive.

Delete a specific snapshot:

# Delete a specific snapshot by timestamp
sudo tmutil deletelocalsnapshots 2024-01-15-093042

Delete all local snapshots (use with caution):

# Delete all local snapshots from the root volume
sudo tmutil deletelocalsnapshots /

Delete snapshots older than a certain date:

# List snapshots and delete old ones manually
tmutil listlocalsnapshots / | while read snapshot; do
  # Extract date portion and compare
  echo "Snapshot: $snapshot"
done

After deleting snapshots, retry your Git operation:

git checkout <branch>
# or whatever command was failing

If deleting snapshots doesn't help or you want a cleaner approach, use the thinlocalsnapshots command to let macOS intelligently remove snapshots:

# Thin local snapshots, reclaiming up to 10GB
# The number is in bytes
sudo tmutil thinlocalsnapshots / 10000000000 4

# The '4' at the end is the urgency level (1-4)
# 4 = most aggressive, deletes more snapshots

This approach is safer than manually deleting all snapshots because macOS will prioritize removing older or less critical snapshots while potentially keeping recent ones.

You can also thin to a specific amount of free space:

# Free up space until you have 50GB free
# Adjust the byte count as needed
sudo tmutil thinlocalsnapshots / 50000000000 4

Connecting your backup drive and completing a backup can help macOS clean up local snapshots:

1. Connect your Time Machine backup drive
2. Start a backup:
- Click Time Machine in the menu bar > "Back Up Now"
- Or via terminal: tmutil startbackup

3. Wait for the backup to complete

When Time Machine successfully backs up to an external drive, it often clears local snapshots that are now redundant. This can release the file locks causing your Git errors.

# Start backup from terminal
tmutil startbackup

# Wait for completion
tmutil status

# When done, retry Git
git pull origin main

If you use Time Machine over network (NAS, Time Capsule), ensure the network location is accessible.

If the error persists and you need to complete your Git work urgently, temporarily disable Time Machine:

Via System Settings (macOS Ventura+):
1. Open System Settings
2. Go to General > Time Machine
3. Toggle off Time Machine or click "Options" and pause backups

Via System Preferences (older macOS):
1. Open System Preferences > Time Machine
2. Toggle the switch to Off

Via terminal:

# Disable Time Machine
sudo tmutil disable

# Perform your Git operations
git checkout feature-branch
git pull origin main

# Re-enable Time Machine when done
sudo tmutil enable

Important: Remember to re-enable Time Machine after completing your Git operations. Running without backups is risky.

After clearing snapshots, you may need to reset Git's state before retrying:

# Clean up any partial state from the failed operation
git reset --hard HEAD

# Clean untracked files if needed (careful - this deletes untracked files!)
git clean -fd

# Now retry your operation
git checkout main
git pull origin main

If you were in the middle of a merge or rebase:

# Abort the in-progress operation
git merge --abort
# or
git rebase --abort

# Then retry
git pull origin main

If the error mentioned specific files, you can try removing them manually first:

# If Git said it couldn't unlink 'src/file.js'
rm -f src/file.js

# Then retry the Git command
git checkout main

Low disk space can prevent macOS from automatically pruning local snapshots. Check your available space:

# Check disk usage
df -h /

# See what's using space
sudo du -sh /* 2>/dev/null | sort -h

Free up disk space:
1. Empty the Trash
2. Clear Downloads folder
3. Remove old iOS backups: ~/Library/Application Support/MobileSync/Backup/
4. Clear Xcode derived data: rm -rf ~/Library/Developer/Xcode/DerivedData/*
5. Use "Manage Storage" in System Settings > General > Storage

After freeing space, macOS should automatically prune old local snapshots. You can also trigger this with:

# Encourage macOS to clean up
sudo tmutil thinlocalsnapshots / 1000000000 4