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This article applies to Code42 for Enterprise version 4.

Other available versions:

Version 6 | Version 5icon.qnmark.png

Code42 Support

Unable to connect to the backup engine

This article applies to Code42 for Enterprise version 4.

Other available versions:

Version 6 | Version 5icon.qnmark.png


If you attempt to start the CrashPlan app and it gets stuck on the CrashPlan splash screen displaying the error, Unable to connect to backup engine, retry?, this article can help you troubleshoot the issue. This error usually occurs because the CrashPlan service is not running.

Under the hood

The CrashPlan app consists of two parts:

  • Graphical user interface that the user interacts with
  • CrashPlan service that runs in the background

These two pieces communicate over a local network connection that is built into every computer. When the CrashPlan app starts, the graphical user interface and CrashPlan service attempt to connect to each other. If they can't connect, the graphical user interface won't start.

Unable To Connect To Backup Engine

Recommended solutions (all operating systems)

The recommendations below apply to all operating systems. These are the resolutions that most often resolve the issue. If these solutions don't resolve the issue, see the additional recommendations for your specific operating system below.

Restart the CrashPlan service

The first thing to try on all platforms is to restart the CrashPlan service. If this doesn't resolve the issue, continue to the recommended solutions below.

Out of memory

If you have a large backup selection (more than 1 TB or 1 million files), you may need to allocate more memory to the CrashPlan app. When CrashPlan runs into this memory limit, the CrashPlan service is not able to run, resulting in the Unable to connect to backup engine message. If you have a large file selection backing up, refer to our troubleshooting article on this topic to address the issue.

Remove CrashPlan application files from previous installations

If the CrashPlan app was previously installed per user, uninstalling and reinstalling for everyone (the default installation) causes an error. To resolve this issue, complete the following steps:

  1. Locate the .ui_info file from the previous per-user installation:
    • Windows Vista, 7, 8, and 10C:\Users\<username>\AppData\<Local or Roaming>\CrashPlan
    • Windows XPC:\Documents and Settings\<username>\Application Data\CrashPlan
    • Mac/Users/<username>/Library/Application Support/CrashPlan
      On Mac, the .ui_info file is hidden by default.  See Lifewire's tutorial to show hidden files to view the .ui_info file. 
  2. Delete the .ui_info file.
    Deleting this file does not harm your CrashPlan backup. It is a file left over from a previous installation and it is no longer necessary.
  3. Restart the CrashPlan notification area or menu bar app:
    • Windows: From the Windows Start menu, select CrashPlan > CrashPlan Tray.
    • Mac: Open the CrashPlan app and select Settings > Launch.

Uninstall and reinstall

If you're still having trouble, the next step is to uninstall and reinstall the CrashPlan app.

Check for port conflicts

If the CrashPlan service still does not connect, verify that another application is not already using the required ports. While CrashPlan may not require these ports all of the time, the CrashPlan service still must prepare them for use.

Recommended solutions (Mac)

If the recommended solutions for all platforms didn't resolve the problem, try the following recommendations for Mac.

CrashPlan version 3.6.3

There is a known issue in the 3.6.3 version of the CrashPlan app that impacts systems running Mac with case-sensitive file systems. This issue results in the Unable to connect to the backup engine message upon opening the CrashPlan app. See our troubleshooting guide to resolve the issue.

CrashPlan version 3.4.1 and earlier

The CrashPlan app version 3.4.1 and earlier is not compatible with Java 1.7. On October 16, 2012, Apple released an update to Java 1.6 that could cause your computer to use Java 1.7 by default. This WikiHow article can help you determine which versions of Java are installed on your computer.

  • If you are running Java 1.6, CrashPlan still works.
  • If you are running Java 1.6 and Java 1.7, Apple's update defaults to Java 1.7, and CrashPlan no longer works. Refer to our troubleshooting article on this topic to correct the issue.

Recommended solutions (Windows)

If the recommended solutions for all platforms didn't resolve the problem, try the following recommendations for Windows.

Verify that the CrashPlan service is enabled

You can verify that the CrashPlan service enabled from the Microsoft Services menu:

  1. Open the Start menu.
  2. Locate and open the Services program:
    • Windows 10: Click the Search box, type Services and then press Enter.
    • Windows Vista, 7, and 8: From the Start menu search bar, type services.msc and then press Enter.
    • Windows XP: From the Start menu, select Run. Type services.msc and then press Enter.
  3. Double-click CrashPlan Backup Service.
    The CrashPlan Backup Service Properties window opens.
  4. Ensure that the Startup Type is set to Automatic.
  5. If the Start service status button is available, click it to start the CrashPlan service.
  6. Click Apply if you made changes to your settings, then close the window.

Failure after Windows restart

If the Unable to connect to backup engine error returns after each reboot, this is usually caused by a Windows service causing a loopback conflict with the CrashPlan service at boot. To resolve this, you can delay CrashPlan's startup:

  1. Open the properties window for the CrashPlan Backup Service using the directions above.
  2. On the General tab, change Automatic to Automatic (delayed start).
    Windows XP only: If the Automatic (delayed start) option is unavailable, click the Recovery tab and set First failure and Second failure to Restart the Service.
  3. Click OK.

Recommended solution (Linux)

If your system language is not set to English when the CrashPlan app is installed, the application starts and backs up but fails to open after rebooting the computer. To ensure that the CrashPlan app is able to open after rebooting, perform the following steps:

  1. Uninstall the CrashPlan app.
  2. Change the Linux system language to English.
    Consult the documentation for your Linux distribution for instructions on changing the system language.
  3. Install the CrashPlan app.
  4. Change the Linux system language back to your language.
    CrashPlan now opens normally.

Alternate solution

Manually starting the CrashPlan service after rebooting your computer allows you to open the CrashPlan app.

Starting the CrashPlan service
Using this method to start the CrashPlan service does not persist after restarting the computer and must be reapplied after every restart.