We saw PRVG-2019 when we use Oracle cluster verification utility (CLUVFY) to check if there's any problem before grid infrastructure installation.
PRVG-2019 : Check for equivalence of user "grid" from node
PRVG-2019 : Check for equivalence of user "oracle" from node
PRVG-2019 means that the cluster verification utility cannot reach the other node through SSH to perform a thorough check before grid installation.
This is because we have not set user equivalency for grid yet, so this error is pretty normal before grid installation. To overcome the error, you can establish SSH equivalency for grid before installation. PRVG-2019 will be gone.