During migration, the Migrate Virtual Machine wizard checks the destination host for compatibility with the migrating virtual machine using a number of criteria.

When you select a host, the Compatibility panel at the bottom of the Migrate Virtual Machine wizard displays information about the compatibility of the selected host or cluster with the virtual machine’s configuration.

If the virtual machine is compatible, the panel displays the message, Validation succeeded. If the virtual machine is not compatible with either the host’s or cluster’s configured networks or datastores, the compatibility window can display both warnings and errors:

Warning messages do not disable migration. Often the migration is justified and you can continue with the migration despite the warnings.

Errors can disable migration if there are no error-free destination hosts among the selected destination hosts. In this case, the Next button is disabled.

For clusters, the network and datastore configurations are taken into account when checking compatibility issues. For hosts, the individual host’s configuration is used. A possible problem might be that VMotion is not enabled on one or both hosts.

A specific host CPU feature’s effects on compatibility are dependent on whether ESX/ESXi exposes or hides them from virtual machines.

Features that are exposed to virtual machines are not compatible when they are mismatched.

Features that are not exposed to virtual machines are compatible regardless of mismatches.

Specific items of virtual machine hardware can also cause compatibility issues. For example, a virtual machine using an enhanced vmxnet virtual NIC cannot be migrated to a host running a version of ESX that does not support enhanced vmxnet.