Does this happen during validation, or only during execution? If only during validation, try holding the Shift key as you click the validate icon, or click the Retry link if that is shown. This will avoid using cached data, which can sometimes lead to errors like you’re seeing because of the way that data is serialized to the cache during one validation and then deserialized from the cache on a subsequent validation. Values of types such as Integer will become normalized to other types like BigInteger in the process of serialization/deserialization.