This particular issue is noticed after we add or un mount datastores to/from the ESXi hosts with vSphere 6 version.
If you see the log file ‘/var/log/hostd.log’ you will see a similar issue triggered for the respective hosts as shown below
use ‘cat /var/log/hostd.log | grep VMFS’ command to filter the logs
Actual root cause of the issue is when a LUN is presented to the ESXi hosts for the 1st time, ESXi hosts fails to detect the version of the file system. Hence, hosts are unable to match with the available list of valid file system versions.
To resolve this issue, you either have to restart the management agents or reboot the ESXi hosts.
If you have production setup where VMs are running on the respective hosts, restarting management agents on those hosts does not impact the power state of the virtual machines.
After you restart the management agents ot reboot the hosts, VMFS volumes upgrades to the correct required version and issue will be resolved.
You will face this issue when the ESXi hosts added to the vCenter, where vCenter version is lower than vCenter server 6.0 update 2.
If you want to upgrade the vCenter to above version, you can download the respective software version from vCenter Server 6.0 update 2
Reference – VMware KB2109735