backup fails: Unable to acquire lock "/var/log/proxmox-backup/tasks/.active.lock

R

RobFantini

Famous Member
May 24, 2012
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Boston,Mass
Hello . I've seen mention of this at the German forum and a thread here [ which the poster never replied to the help given].

on one of 5 nodes in the last week the first vm fails a pbs backup. from backup fail emails:
Code: 
pve-15  107: 2026-05-18 00:00:16 ERROR: VM 107 qmp command 'backup' failed - backup connect failed: command error: Unable to acquire lock
"/var/log/proxmox-backup/tasks/.active.lock" - Interrupted system call (os error 4)
  - that was the 1st vm   107     phone-system-2025    err       16s     0 B        null                           

pve-15 111: 2026-05-22 00:00:16 ERROR: VM 111 qmp command 'backup' failed - backup connect failed: command error: Unable to acquire lock
"/var/log/proxmox-backup/tasks/.active.lock" - Interrupted system call (os error 4)
  - that was the 1st vm.  note diff vm number  .  phone-system-2025 got migrated before
  - 111     nextcloud          err       16s     0 B        null       
 
pve-15 111: 2026-05-26 00:00:16 ERROR: VM 111 qmp command 'backup' failed - backup connect failed: command error: Unable to
acquire lock "/var/log/proxmox-backup/tasks/.active.lock" - Interrupted system call (os error 4)


only the first vm backup fails. the remainder all get backed up.
these pbs backup start at 00:00
at 17:00 we do old type vzdump backup to local storage

on two nodes these directories do not exist. I do not understand why /var/log/proxmox-backup would not exist. anyway pve2 does not have /var/log/proxmox-backup and backups work.

Code: 
root@pve2:[~]:# ls -l /var/log/proxmox-backup/tasks/.active.lock
ls: cannot access '/var/log/proxmox-backup/tasks/.active.lock': No such file or directory
root@pve2:[~]:# ls -l /var/log/proxmox-backup/tasks
ls: cannot access '/var/log/proxmox-backup/tasks': No such file or directory
root@pve2:[~]:# ls -l /var/log/proxmox-backup
ls: cannot access '/var/log/proxmox-backup': No such file or directory


root@pve-15:[/etc/pve]:# ls -l /var/log/proxmox-backup/tasks/.active.lock
ls: cannot access '/var/log/proxmox-backup/tasks/.active.lock': No such file or directory
root@pve-15:[/etc/pve]:# ls -l /var/log/proxmox-backup/tasks
ls: cannot access '/var/log/proxmox-backup/tasks': No such file or directory
root@pve-15:[/etc/pve]:# ls -l /var/log/proxmox-backup
ls: cannot access '/var/log/proxmox-backup': No such file or directory

I just did a backup of vm 111 and it worked.

Let me know suggestions to fix or if more info is needed.
 
this is an error from the PBS side, please check the logs there..
 
Code: 
journalctl -b  -p3 -u proxmox-backup-proxy --since "yesterday"

May 26 00:00:15 pbs-new proxmox-backup-proxy[2419]: error writing task result to the tasklog
May 26 00:00:16 pbs-new proxmox-backup-proxy[2419]: GET //api2/json/backup?backup-id=111&backup-time=1779768000&backup-type=vm&benchmark=false&debug=false&store=daily: 400 Bad Request: [client [::ffff:10.11.12.15]:39962] Unable to acquire lock "/var/log/proxmox-backup/tasks/.active.lock" - Interrupted system call (os error 4)
May 26 11:48:49 pbs-new proxmox-backup-proxy[2419]: Failed to verify the following snapshots/groups:
May 26 11:48:49 pbs-new proxmox-backup-proxy[2419]:         vm/111/2026-05-26T04:00:00Z
 
note that all 5 nodes use the same pve backup job. so they run at the same time. perhaps I should make a backup job spread out for each node?
 
please post the full journal..
 
also during backups other nodes had the following errors. however the backups succeeded

Code: 
May 26 00:00:12 pve7 pve-ha-lrm[3892712]: VM 101 qmp command failed - VM 101 qmp command 'query-status' failed - got timeout

May 26 00:00:10 pve2 pve-ha-lrm[2594781]: VM 106 qmp command failed - VM 106 qmp command 'query-status' failed - got timeout

May 26 00:00:10 pve11 pve-ha-lrm[3286962]: VM 100 qmp command failed - VM 100 qmp command 'query-status' failed - got timeout
 
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