Only when it is executed inside a serializable transaction
Furthermore, all the data fields in the class must themselves be serializable.
The type {0} in Assembly {1} is not marked as serializable.
The Future object is not serializable, which means that in a highly available environment the handle returned by the callback handler cannot be replicated.
The eventual return type is not specified by any of the asynchronous service interfaces or implementation classes, leaving the return type your choice, which can be any serializable data type.
