A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

An error has occurred during serialization or deserialization.

This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.