How to fix unstable continously synchronizing CrashPlan service

CrashPlan has been backing up my stuff for several years. Been very happy with it and it has already saved me from losing everything in a complete hard drive crash.

The last few months however it as been extremely unstable and never been able to complete a full backup. Which is very very bad. I’ve basically been stuck at 90% for a couple of months and the missing 10% in my case is over 100 GB. A lot of potential loss.


  • Highly unstable user interface.
  • Keeps “synchronizing”.
  • Backup never completes.
  • High CPU usage of the CrashPlan service and memory usage close to 512 MB.

Contacted their customer support and after sending them my CrashPlan log files it turns out the poor CrashPlan service is a Java application and, by default, runs on a JVM limited to 512 MB of memory. Probably usually OK, but I have a lot of files. So basically the service has been garbage collecting itself to death these months and not gotten anywhere.

How to fix it

  1. Open an elevated command prompt.
  2. Stop the CrashPlan service.
    C:\> net stop CrashPlanService
  3. Open the configuration file for the CrashPlan service.
    C:\> notepad %ProgramFiles%\CrashPlan\CrashPlanService.ini
  4. Change -Xmx512M to for example -Xmx1024M or -Xmx2048M, depending on how much memory you have to spare.
  5. Start the CrashPlanService.
    C:\> net start CrashPlanService

If your problem was lack of memory, it should now run more smoothly. Does for me anyways πŸ™‚

  • Michael Sevestre

    It did the trick for me too! Awesome

  • RobertSeattle

    Also seems to have done the trick for me as well but a mere start often fixed this as well. CrashPlan developers really need to take a look at this. Also – the Synch start and stop times should be in the History so we can prove to them how long it is taking.

    • I thought a restart of the service/computer would fix it as well, and right afterwards it did seem like it ran fine, but after a while it just got stuck again.

  • R

    Any idea how to do this on a Mac?

      • trawk

        Apparently regular users don’t have access to this link Torleif. Could you please verify? As a Mac user, I am having the exact same problem you describe so would be very pleased to try out your method.

        • Hm, looks like they must have messed up their forum or something. I can’t access the guide either. Even after logging in :/

    • The_Arsonist

      I had a problem with crash plan crashing a while ago and this was the response I received from crash plan support

      “Please follow the instructions below to allocate more memory to the CrashPlan backup engine.

      Edit the CrashPlan engine’s com.crashplan.engine.plist (“the plist file”) file to allow it to use more java memory. You will need to use Terminal for this, and edit the file using the ‘sudo’ command. When prompted, type in your computer’s Admin password. Note that you will not see the text-cursor move when you do – this is normal.

      1. Stop the backup engine by typing this into the Terminal application:

      sudo launchctl unload /Library/LaunchDaemons/com.crashplan.engine.plist

      2. Run this command to edit the backup engine:

      sudo nano /Library/LaunchDaemons/com.crashplan.engine.plist

      3. In /Library/LaunchDaemons/com.crashplan.engine.plist, find this line: -Xmx512m

      4. Edit that line to something larger such as 640, 768, 896, or 1024. E.g.: -Xmx1024m

      This sets the maximum amount of memory that CrashPlan can use. CrashPlan will not use that much until it needs it. I would recommend starting out setting it to 768, and go higher only if you continue experiencing problems. You can increase it above 1024 if you have a really large file-selection.

      5. Hold the Control key and tap the x key to exit. Choose “y” to confirm it.

      6. You’ll see the prompt “File Name to Write.” Hit enter to save to the existing location.

      7. Start the backup engine by typing:

      sudo launchctl load /Library/LaunchDaemons/com.crashplan.engine.plist

      That’s it”

  • Thank you for saving me hours of research!

  • Ironically the CrashPlanDesktop process often takes over 2 GB of RAM… (while the CrashPlan service is limited at 1 GB by default nowadays)

  • Pete

    I know this is a very old thread, but I wanted to add my experience. I have a workstation that occasionally resets system time to a seemingly random value (Windows). Whenever the system time gets more than 10 minutes out of sync, Crashplan will stop working until the system time is synced back up. Even the GUI will not remain running. Once the system time resets to normal, everything has to re-sync before backup can occur. Once I replaced my BIOS battery, Crashplan became very stable.

  • devopsmikey

    Hi Torleif — are you using Crashplan for home, which is being shutdown in 2018? Do you have any personal recommendations as to what you might be switching to? They suggest their $10/month/device business plan, or Carbonite. Thanks

    • I’m probably moving to Backblaze. Been trying Jottacloud for a while too, but it’s been a bit unstable… they’ve been doing fixes though, so we’ll see. Currently running both… and will remove one around Christmas. πŸ™‚