Labtainers Support

We value your feedback, questions and trouble reports.  Please contact me at: mfthomps at  Or, use GitHub to report issues. 

If you'd like to be notified of updates to the Labtainer framework, please send an email to labtainers-request [at] with 'subscribe' in the Subject field OR by visiting our mail list page.

Troubleshooting suggestions are listed below.  You can update your Labtainers installation by running:

from your labtainers-student directory.  


Virtual machine troubleshooting (problems with the VM appliance)

Labtainers trouble shooting

Developer troubleshooting


Virtual Machine Troubleshooting:

  • VMWare virtual machine windows sometimes become hard to use, depending on your platform.  Try using: "View" / "Autosize" / select "Autofit Guest".
  • If you have trouble installing a 64-bit guest on VirtualBox on Windows 10, refer to this link: Or, run bcdedit /set hypervisorlaunchtype off from an elevated command prompt.   
  • If VMs will not boot, confirm you have enabled VT-x/AMD-v in your BIOS
  • If a VMWare virtual machine becomes unable to reach your network, this can usually be resolved by rebooting your system, e.g., your Mac.  Alternately, these commands often work from within a terminal on the Mac:
    • sudo /Applications/VMware\ --configure
    • sudo /Applications/VMware\ --stop
    • sudo /Applications/VMware\ –start
  • When first starting a VM on Mac OSX, if the VM seems to freeze, i.e., you cannot type or click in the desktop:  use  preferences/security/unlock/privacy "Allow apps below to control your computer"
  • Ubuntu Package manager error (red stop symbol in upper right of desktop):  If an Ubuntu VM reports package errors, try using the "sudo apt-get install -f" command and then reboot. 
  • If your VM disk fills up, e.g., the "df" command shows Use of 100% on the root file system, you can reclaim space by deleting the current lab (or some other) from the labtainer-student directory: <labname> (this will cause you to lose work)
  • If you "opened" the download link rather than downloading the file, your computer may have changed the name of the file from .ova to .ovf.  You will need to change the file name back to ova before you can import the appliance.
  • If a VirtualBox VM network becomes outrageously slow, power off the VM and change the network adaptor type in Settings / Networks / Advanced.  Yeah, that sounds stupid, but it often works. 

Labtainers Troubleshooting

  • If a GUIs fail to open (e.g., firefox or wireshark), and you see an error such as "cannot open display: :0", your X11 socket on the VM may have been corrupted.  On the VM, an ls -l /tmp/.X11-unix should display a socket named "X0".  If it does not, you may need to reboot your VM.
  • Get updates by running (These include fixes to student and instructor environments.)
  • GUI windows may sometimes display as solid black boxes.  Resizing the window, or closing it (e.g., via Esc) and then reopening it will usually force the window to repaint.
  • If labs are unable to reach the Internet, e.g., to ping google, and you are connected to a VPN, try disconnecting the VPN.
  • When starting a new Labtainer, if you see an error such as "No JSON object could be decoded", try updating your installation (per above).
  • If you see this error: "Remote image ... is lacking a base version, it needs to be retagged with trunk/distrib/"  run (from the labtainer-student directory) to update your distribution. 
  • If the "labtainer" (or commands do not do anything, your installation has been corrupted.  You can recover from that as follows:
Go to
Click the link named:   “Download the Labtainer framework” and save the file into your Downloads directory.
Then extract it:
   tar -xf ~/Downloads/labtainer.tar 
Then return to ~/labtainer/labtainer-student and try again.


  • Virtual Machine images were replaced on July 5, 2018.  If you are using older VM images, you might consider transitioning to the newer VM.  Otherwise, running new labs will require large downloads that may consume your VM resources.

Developer Troubleshooting:

  • Get updates by running labtainer/setup_scripts/
  • Periodically use the /labtainer/setup_scripts/ to remove unused images.  This will reclaim disk space consumed when doing many iterations of building the same lab.
  • As a last resort, use the labtainer/setup_scripts/ to fully erase all local Docker images.  Then use to pull in all baseline images (several GB download).
  • If your built labs do not seem to initialize or run the way you wish, look at the /tmp directory on the containers for diagnostics.
  • If your /tmp/ contains lines like "sudo: unable to stat /etc/sudoers: Permission denied" you likely copied a lab between systems, e.g., using a VM shared directory.  That messes up file permissions.  I'd hate to suggest a fix other than to go back and copy lab files using tar and/or scp to retain permissions.


Acknowledgment: This work was supported by NSF grant DUE-1438893. The views expressed in this material are those of the authors and do not reflect the official policy or position of the National Science Foundation, the Naval Postgraduate School, the Department of Defense, or the U.S. Government.