Software⏱️ 4 min read📅 2026-06-11

How to Fix: Time Machine does not back up, "failed with error: 11"

Time Machine backup issue with error code 11 and unknown corrupted file.

Quick Answer: Run Disk Utility's 'First Aid' tool on the affected volume to scan for errors and fix them.

📋 Table of Contents

  1. ⚠️ Common Causes
  2. 🚀 How to Resolve This Issue
  3. ✨ Wrapping Up

Time Machine is refusing to backup files on your Mac, resulting in an error message that says 'failed with error: 11'. This issue can be frustrating, especially when you're trying to protect your important files. The problem often lies in file system inconsistencies or corrupted files.

In this troubleshooting guide, we will walk you through the possible causes and solutions for the Time Machine backup failure error code 11.

⚠️ Common Causes

  • The primary reason for this issue is a mismatch between the event store UUIDs for the Macintosh HD volume. This can happen when the system tries to scan subdirectories on an untrusted volume, resulting in errors during the backup process.
  • Another possible cause is a corrupted file or directory that Time Machine cannot access or read.

🚀 How to Resolve This Issue

Resolving Mismatched Event Store UUIDs

  1. Step 1: Step 1: Open Disk Utility and select the Macintosh HD volume from the list on the left. Click on the 'First Aid' tab at the top of the window.
  2. Step 2: Step 2: Select the 'Repair Disk' option and click 'Continue'. This will attempt to repair any file system errors on the volume, which may resolve the mismatched event store UUIDs issue.
  3. Step 3: Step 3: If the First Aid tool does not fix the issue, you can try using the 'Repair Volume' option instead. This will allow you to manually repair specific files and directories that are causing the error.

Identifying and Removing Corrupted Files

  1. Step 1: Step 1: Open the Terminal app on your Mac and navigate to the directory where Time Machine is trying to access. You can do this by typing 'cd /Volumes/Back-Up 1TB/Backups.backupdb/PF's MacBook' and pressing Enter.
  2. Step 2: Step 2: Use the `mdfind` command to search for any corrupted files on the volume. For example, you can type `mdfind -type f` to find all files on the volume. This will list a long list of files, including the one that caused the error in your original message.
  3. Step 3: Step 3: Once you have identified the corrupted file, you can use the `rm` command to delete it. For example, if the file is named 'Drone Low Pulse.caf', you would type `rm /Library/Audio/Apple Loops/Apple/Apple Loops for Soundtrack Pro/Detroit Chop Shop/Sci-Fi/Drone Low Pulse.caf' and press Enter.

✨ Wrapping Up

To summarize, the Time Machine backup failure error code 11 is often caused by a mismatched event store UUIDs or corrupted files on the Macintosh HD volume. By following these steps, you should be able to resolve the issue and get your Time Machine backups working again.

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