Cannot serialize; nested exception is org.springframework.core.serializer.support.SerializationFailedException: Failed to serialize object using DefaultSerializer; nested exception is java.lang.IllegalArgumentException: DefaultSerializer requires a Serializable payload but received an object of type [com.itheima.domain.Customer]

这个错误通常意味着对象没有实现 Serializable 接口。如果你想将一个对象序列化，就必须要让它实现 Serializable 接口，这样才能在网络中传输或在磁盘上保存。建议您检查您的代码，将所有需要序列化的对象都实现 Serializable 接口。