Cannot monitor VM status and Host with error

Hello,

My version is 5.4.6 with KVM

Sunstone today I suddenly find VM is showing “UNKNOWN” status under Instances -VMs.

Also, the host under Infrastructure -> Hosts is showing ERROR. And the oned.log also showing following error

Mon Feb 5 12:53:22 2018 [Z0][ONE][E]: Error monitoring Host node1.abc.com (1): error: failed to connect to the hypervisor
error: error from service: CheckAuthorization: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
ERROR MESSAGE --8<------
Error executing kvm.rb
ERROR MESSAGE ------>8–
ARCH=x86_64
MODELNAME=“Intel® Xeon® CPU E3-1230 V2 @ 3.30GHz”

and /var/log/messages is repeating showing

Feb 5 12:54:22 opennebula libvirtd: 2018-02-05 04:54:22.940+0000: 1245: error : virNetSocketReadWire:1808 : End of file while reading data: Input/output error
Feb 5 12:54:53 opennebula libvirtd: 2018-02-05 04:54:53.016+0000: 1269: error : virDBusCall:1570 : error from service: CheckAuthorization: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
Feb 5 12:54:53 opennebula libvirtd: 2018-02-05 04:54:53.016+0000: 1245: error : virNetSocketReadWire:1808 : End of file while reading data: Input/output error

Could you please advise how I can trace and fix this problem?

Thanks!

Related to https://forum.opennebula.io/t/hosts-entering-the-error-state?