The below steps can be performed to overcome this :
(1) Check the share name of the datastore
In case if it is using FQDN.domain.com /Datashare
Try changing it to FDQN.DOMAIN.COM /Datashare
The caps in the FQDN makes the variance in the symbolic name that can cause the problem
(2) If the above step doesn't help , proceed to the below step
(a) List the mounted datastores on the host :
esxcli storage nfs list
(b) Make a note of the NFS datastore from step 1. Run this command to delete the NFS mount:
esxcli storage nfs remove -v NFS_Datastore_Name
Note: This operation does not delete the information on the share, it unmounts the share from the host. If the NFS datastore is being used by either a virtual machine or a third party script, you may see this error:
Error performing operation: NFS Error: Unable to Unmount filesystem: Busy.
To add the datastore:
esxcli storage nfs add -H NFS_IP|NFS_HOSTNAME -s Share_mount_point_on_the_NFS -v DatastoreName
Restart Management Agents if the above step doesn't works. Proceed to the below step in case issue isn't still rectified.
(3) Remove the share permissions for the host from NFS Storage end and re-add it
Add again via the below command
esxcli storage nfs add -H NFS_IP|NFS_HOSTNAME -s Share_mount_point_on_the_NFS -v DatastoreName