Key indicators that CrashPlan cannot back up:

The backup progress bar never reaches 100%

The error message “Cannot backup n files” appears in the History log


CrashPlan apps running on Mac OS X

Under the hood

Typically, when files fail to back up on a Mac, it’s due to the type of files being backed up. Many of the files that cannot back up are located in the following directories:

  • /Library
  • /System
  • /Applications
  • /Users/[User]/Library

Files located in the Library, System, and Applications folders contain system files that your Mac needs to work correctly. CrashPlan is designed to back up and restore personal files, not system and application files. If these directories are included in your backup file selection, they could interfere with the priority in which your personal files are backed up.

The files found in your user Library folder, are mostly temporary application or cache files. Since CrashPlan prioritizes the most recently changed files first, including this folder in your backup selection may cause CrashPlan to spend too much time and effort trying to keep up with constantly changing cache files (like your web browser cache). This can hinder the progress of more important personal files you truly want to be backed up.


You can use either of the methods below to identify which files are failing to back up.

Determining what’s not backing up (basic)

  1. Open the Finder.
  2. Press Command+Shift+G, and paste the following file path into the dialogue:
    • /Library/Logs/CrashPlan
  3. Press Enter.
  4. Open the backup_files.log.0 file with TextEdit.

This document lists every file that CrashPlan has backed up. However, any log lines beginning with a “W” signify a file CrashPlan wasn’t able to back up at that time.

Determining what’s not backing up (advanced)

  1. Open Terminal.
  2. Enter the following command:
  • Installed for everyone: grep “^W” /Library/Logs/CrashPlan/backup_files.log.0 | less
  • Installed per user: grep “^W” ~/Library/Logs/CrashPlan/backup_files.log.0 | less

This command lists any file that failed to back up using CrashPlan.

Recommended solution

Modify the CrashPlan file selection accordingly so that only personal files are backed up.

Written by: Sithila Konara

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