KVM: Dialog shows "Error polling connection 'qemu:///system'"

Issue

• On virtual machine manager of host, following dialog message was shown.

Error polling connection 'qemu:///system': internal error client socket is closed

• This issue was recovered by reconnecting from virtual machine manager.
• When clicking 'Detail', following messages were shown.

Error polling connection 'qemu:///system': internal error client socket is closed
Traceback (most recent call last): 
 File "/usr/share/virt-manager/virtManager/engine.py", line 440, in_tick conn.tick()
 File "/usr/share/virt-manager/virtManager/connection.py", line 1433, in tick self.hostinfo = self.vmm.getinfo()
 File "/usr/lib64/python2.6/site-packages/libvirt.py", line 3383, in getinfo if ret is None: raise libvirtError ('virNodeGetInfo() failed', conn=self)
libvirtError: internal error client socket is closed