VM への接続に失敗し error: Failed to connect socket to '@/sysadmin/.libvirt/libvirt-sock': Connection refused エラーが出力される

Issue

KVM 仮想マシンのコンソールに接続できません。

以下のようなエラーメッセージが出力されます。

"error:Failed to connect socket to '@/sysadmin/.libvirt/libvirt-sock':Connection refused"

サーバーからの出力:

sudo virsh list --all

[sudo] password for userxx:
 Id Name                 State
----------------------------------
 18 vm1             running
 20 vm2             running


virsh console vm1

error:Failed to reconnect to the hypervisor
error: no valid connection
error:Failed to connect socket to '@/sysadmin/.libvirt/libvirt-sock':Connection refused

以下のエラーも /var/log/libvirt/libvirtd.log で確認できます。

 error : daemonStreamHandleAbort:590 : stream aborted at client request
 error : virFileOpenAsNoFork:668 : failed to create file '/mnt/dumpfile':Permission denied
 error : virFileOpenAsNoFork:668 : failed to create file '/mnt/dumpfile': Permission denied
 error : qemuOpenFile:2332 :Error from child process creating '/mnt/dumpfile':Permission denied
 error : virFileOpenAsNoFork:687 : cannot chown '/mnt/dumpfile' to (0, 0):Operation not permitted
 error : virFileOpenAsNoFork:687 : cannot chown '/mnt/dumpfile' to (107, 107):Operation not permitted
 error : qemuOpenFile:2332 :Error from child process creating '/mnt/dumpfile':Operation not permitted