Article ID: 121514, created on May 9, 2014, last review on Apr 13, 2015

  • Applies to:
  • Virtuozzo 6.0


prlctl commands hang and then fail with error when timeout is reached.

# prlctl list -a
Login failed: Unable to connect to the server "localhost". An invalid response has been received from the server. Make sure that Parallels Server is running on the server "localhost" and is up to date and try again.


This issue might happen if some filesystem, where VMs or VM templates are registered, has become inaccessible, operations (such as df) with its mount point hang endlessly:

[root@PCS1 ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda3             394G   10G  364G   3% /
tmpfs                  32G  5.2M   32G   1% /dev/shm
/dev/sda1             2.0G  122M  1.8G   7% /boot
                      3.2T  467G  2.6T  16% /pstorage
                    40G  9.4G   29G  25% /vz
                    9.9G  335M  9.1G   4% /pstorage/cluster-mds/ploop_mds.img.mnt

Usually it's NFS file system which stores VM templates. NFS mount point tend to be the most vulnerable and fragile:

[root@PCS1 ~]# mount | grep nfs on /templates type nfs (rw,timeo=14,intr,addr=

In such cases you will find nfs-related errors in dmesg:

[root@PCS1 ~]# dmesg | grep nfs
[10405249.292138] ct0 nfs: server not responding, still trying
[10405259.798122] ct0 nfs: server not responding, still trying


Find the reason why operations with this mount point hang, fix the root cause. Often it's due to inaccessible NFS server.

Search Words

Unable to connect to the server "localhost"

prlctl hang

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