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CrashPlan Support

Reading CrashPlan App Log Files

Applies to:
  • CrashPlan for Home
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This article is intended for CrashPlan for Home users. For Code42 CrashPlan and CrashPlan for Small Business documentation, read this page on our enterprise support site.


This article provides information about the CrashPlan app's log files, including:

  • Log file locations
  • Short descriptions of important log files
  • How to use logs to pinpoint common issues with the CrashPlan app

For details about how to send your log files to a Customer Champion, see Sending CrashPlan Log Files To Support.

Log file locations

The table below shows the location of the log files in the file system for different operating systems.

Note: When you open the log folder, you may notice multiple copies of each log file, e.g. service.log.0, service.log.1, service.log.2, etc. To keep log file sizes under control, logs "roll over" into a new log file after they reach a certain size, and older logs are eventually purged. The lower the number appended to the log name, the newer the log file. For example, service.log.0 is the most recent service log.

  • Windows Vista, 7, 8, 10, Server 2008, and Server 2012
    • Installed for everyone: C:\ProgramData\CrashPlan\log
      To view this hidden folder, open a file browser and paste the path in the address bar.
    • Installed per user: C:\Users\<username>\AppData\<Local|Roaming>\CrashPlan\log
      To view this hidden folder, open a file browser and paste the path in the address bar.
  • Windows XP
    • Installed for everyone: C:\Documents and Settings\All Users\Application Data\CrashPlan\log
      To view this hidden folder, open a file browser and paste the path in the address bar.
    • Installed per user: C:\Documents and Settings\<username>\Application Data\CrashPlan\log
      To view this hidden folder, open a file browser and paste the path in the address bar.
  • OS X
    • Installed for everyone: /Library/Logs/CrashPlan
    • Installed per user: ~/Library/Logs/CrashPlan
  • Linux: /usr/local/crashplan/log

Log file descriptions


App.log contains general configuration information about your computer and CrashPlan. Information in the app.log includes:

  • Operating system version
  • Java version
  • CrashPlan version
  • Licensing overview
  • CrashPlan app settings
  • Backup destination information


Service.log is the main log file written by the CrashPlan service. It logs warnings and exceptions, so it is usually the main log file used for troubleshooting.


Backup_files.log contains a list of files that CrashPlan has attempted to back up. Information found in backup_files.log includes:

  • Backup success or failure (an "I" means that the file backed up successfully; a "W" means that the file failed to back up)
  • Date and time
  • Destination GUID
  • File name and path
  • File size


Similar to backup_files.log, restore_files.log contains a list of file names and paths for each restore attempt.


History.log mirrors what you see in the History tab of the CrashPlan app. It contains a high-level overview of what the CrashPlan app has been doing, including:

  • Backups starting and stopping
  • File scans starting or stopping
  • Amount of data backed up
  • Backup speed

Troubleshooting the CrashPlan app using logs

To read the files, navigate to the log folder and open the log with a text editor. More advanced users may prefer to use the Command Line or Terminal.

When reading through the logs, it is often helpful to search for WARN as a starting point.

Common errors found in service.log

Sample log messages are included below to illustrate how some common issues appear in the logs.

Unable to connect to the backup engine

If you see an "Unable to connect to the backup engine" message when you try to open the CrashPlan app, and the below error appears in service.log on Windows:

  1. Open services.msc
  2. Open the CrashPlan Backup Service's properties pane
  3. Set the "Startup Type" to "Automatic (delayed start)."
[03.29.13 12:51:12.872 WARN    main                 com.backup42.service.CPService          ] Unexpected IO Exception constructing selector engine - Unable to establish loopback connection, java.lang.RuntimeException: Unexpected IO Exception constructing selector engine - Unable to establish loopback connection

For more details, see Unable to connect to the backup engine.

Out of memory error

One extremely common reason for the "unable to connect to the backup engine" messages is that the backup engine is running out of memory. This will be visible in the service.log ("OutOfMemoryError") as shown below. See CrashPlan Runs Out Of Memory And Crashes for complete details.

[09.23.12 22:33:02.273 ERROR   QPub-BackupMgr       backup42.service.backup.BackupController] OutOfMemoryError occurred...RESTARTING! message=OutOfMemoryError in BackupQueue!

Client cache issues

Client cache issues can manifest themselves in a few different ways, including: some or all files missing from the Restore tab, stopped backups, incorrect reports, and incorrect file selection size.

[12.21.12 12:12:01.441 WARN    W964862003_BckpSel   m.code42.backup.manifest.ManifestManager] Exception initializing ManifestManager java.lang.IllegalArgumentException: Malformed \uxxxx encoding.; MM[BT 525528945129975616>42: openCount=1, initialized = false, = false, C:\ProgramData\CrashPlan\cache\42]

[05.11.12 08:45:22.921 WARN    W471137477_ScanWrkr  com.code42.bplusj.BplusTreeIndexFile    ] Exception calling Commit() while closing BplusTreeIndexFile@1379711510[ path = C:\ProgramData\CrashPlan\cache\cpgft1x, keyLength = 20],

[05.16.12 13:03:06.109 INFO    MQ-Peer-1            com.code42.backup.BackupClient          ] BC[525528942342975616>42:: SYNC:: Manifest validation failed.
[05.16.12 13:03:06.110 WARN    MQ-Peer-1            com.code42.backup.BackupClient          ] BC[525528942342975616>42:: SYNC:: Replacing empty local target manifest files with remote server files!!

Real-time file watching problems

Real-time file watching can have issues that manifest slightly differently on Mac OS X and Linux.


[08.30.12 17:13:27.274 WARN W202972748_SpotQW com.code42.os.mac.spotlight.Spotlight ] Exception in getStringFromCFStringRef(): 64bit, e=java.nio.BufferUnderflowException


12.06.10 04:29:40.426 WARNING W449507565_ScanWrkr ] Unable to add watch for path /home/erik/Desktop/, errno: 28

Identifying what files are backed up using backup_files.log

Files are failing to back up

Lines that begin with a "W" indicate files that are failing to back up. You can also identify these files by searching backup_files.log for the string "Unable to backup".

A file that is failing to back up looks like this:

W 01/06/13 12:00PM 42  - C:\Users\John\Blackberry\Backup\BlackBerry Tour 9630-1.ipd

A file backing up successfully will have an "I" at the start of the line:

I 01/06/13 12:00PM 42 50cd0afdb853e65f1f47c31407ce9a4a 0 C:\Users\Jill\Documents\Outlook Files\outlook.pst (200483653) [1,0,200483653,0,0,0,0]

Is my backup starting over?

Using the backup_files.log, you can identify if a file is being backed up for the first time. The first two numbers summarize CrashPlan's analysis of the file:

  • First number identifies new data blocks that need to be backed up
  • Second number identifies old data blocks that have already backed up

If the first number is greater than zero, and the second number is zero, then it's a new file that's backing up for the first time. For example:


If the first number in the bracketed sequence is zero, and the second number is greater than zero, then it's an existing file that has already backed up. There is nothing new to back up. For example:


If both the first and second numbers are greater than zero, then it's an existing file that has already backed up but there is a new version that needs backing up. For example: