This article shows how to change the configuration of the Veeam server that backing up virtual machines with HA status "stopped" works.
Troubleshooting
When securing Proxmox VE VMs with the help of Veeam, the following error notification may appear:
"01/09/2025 7:28:08 AM:: hostname-machine: Failed to perform backup: Failed to connect the NBD server to the hypervisor host".
The reason for this is that the virtual machine under Proxmox has the HA status "stopped", which means that the Veeam server cannot reach the virtual machine and therefore cannot back it up.
Solution
Search for the installation directory of your Veeam server and in it the file "appsettings.json"
Hint: The standard path is C:\Program Files\Veeam\Plugins\PVE\Service\appsettings.json
Open the file with administrator rights and change the value from <"LockVmOnBackup": false, > to <"LockVmOnBackup": true,>
Restart VeeamPVESvc to make the changes effective
Hint: Verify whether backups or restore operations are running; if so, wait for them to finish or stop them.
The VM is then locked during the backup job, and the backup job runs even with the HA status set to "stopped".
More information
If errors appear during the backup, the VM stays in locked state. You can unlock the VM with "qm unlock <VM-number>".
During the backup, it may be that Proxmox protocols some errors, as the VM can not be stopped due to the backup. This mistake can be ignored, as the backup is still completed successfully. However, it is recommended to hide this message in the corresponding monitoring system.
Niklas Pauli works in the product management team at Thomas-Krenn. He completed his general university entrance qualification at Freyung High School and then his training as an IT specialist for system integration at Thomas-Krenn.AG. After completing his training, he continued to work in the areas of Proxmox VE incl. Ceph, backup (Proxmox, Veeam, SEP). He is also a regular writer for the Thomas-Krenn-Wiki.
Alina has been working at Thomas-Krenn.AG since 2024. After her training as multilingual business assistant, she got her job as assistant of the Product Management and is responsible for the translation of texts and for the organisation of the department.
wiki
