This article provides some troubleshooting tips for the issue “can’t lock file in Proxmox.” Bobcares, as a part of our Proxmox Support Services, offers solutions to every query that comes our way.

Can’t Lock File In Proxmox

The below “Cluster log” appears when attempting to “Stop” or “Shutdown” a virtual machine from the Proxmox (PVE) web GUI.

How to troubleshoot it?

We can fix the error manually or by using scripts. Let’s look into the details of the solution available.

Method 1

Manually removing the lock from the path:

/run/lock/qemu-server
# The file will be
/run/lock/qemu-server/lock-100.conf
/run/lock/qemu-server/lock-102.conf
...
# Make sure only delete the correct one
# Manually unlock again (100 is the VM id)
qm unlock 100

Method 2

We can remove the lock using an automated bash script.

• Firstly, open Proxmox web GUI.
• Then click on “>_ Shell” to launch Shell for Proxmox.
• Now use the below command to create a “killvm.sh” file.

  nano killvm.sh

   
• Choose the script we want to use, then copy and paste it into the nano editor.
• Here, we use the simple script:

  #!/bin/sh
  echo
  echo '-----AUTHOR: https://bobcares.com-----'
  echo
  echo '---Existing locks---'
  qm unlock $1
  ls -l /run/lock/qemu-server
  rm -f /run/lock/qemu-server/lock-$1.conf
  qm unlock $1
  echo
  echo '---Remaining locks---'
  ls -l /run/lock/qemu-server
• In order to Exit and Save the file, use Ctrl + X, Y, and Enter keys.
• Permit the script to run as a program.

  chmod +x killvm.sh

   
• Using the following command, we can now quickly remove locks using the bash script.

  # ./killvm.sh VMID
  #e.g.
  ./killvm.sh 202

Method 3

If we run the “shutdown” action on a VM and it fails (for example, because the guest refuses to comply), the VM remains locked while the shutdown action timeouts. To avoid the timeout, we can either cancel the shutdown operation in the event log or run “qm unlock 100.” Then use the “stop” command instead.

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Conclusion

To conclude, we have included some of the troubleshooting tips from our Support team for the “can’t lock file in Proxmox” issue.