Raised when an unsupported argument type is set as a job argument. We currently support String, Integer, Float, NilClass, TrueClass, FalseClass, BigDecimal, Symbol, Date, Time, DateTime, ActiveSupport::TimeWithZone, ActiveSupport::Duration, Hash, ActiveSupport::HashWithIndifferentAccess, Array, Range or GlobalID::Identification instances, although this can be extended by adding custom serializers. Raised if you set the key for a Hash something else than a string or a symbol. Also raised when trying to serialize an object which can't be identified with a GlobalID - such as an unpersisted Active Record model.