Error "EaiFlagDeleteAttribute field is required" when upgrading from an older Chris21 connector

When upgrading from a pre-UNIFYBroker v5 Chris21 environment I copied the Connector configuration XML across directly.  When associating the Chris21 Connector to the new v5 Agent, there was a UI error on save:

This happened because the newer version of the Chris21 Agent/Connector package has an additional attribute in the XML configuration that wasn't previously present (and UNIFYBroker doesn't automatically add it).

The solution is to edit the XML configuration file to add the attribute by hand then restart the UNIFYBroker service:

The value used for the attribute (eaiFlagDeleteAttribute="eaiunifyfl") were obtained by manually creating a new Chris21 Connector to see what value the system assigned to the attribute.