同样，提供服务端也是报错
2019-12-05 12:00:55.144 WARN 7412 --- [w I/O worker #7] c.a.d.r.p.dubbo.DecodeableRpcInvocation : [DUBBO] Decode rpc invocation failed: expected integer at 0x12 java.lang.String (Ljava/lang/String;), dubbo version: 2.8.4a, current host: 192.168.1.103 com.alibaba.com.caucho.hessian.io.HessianProtocolException: expected integer at 0x12 java.lang.String (Ljava/lang/String;) at com.alibaba.com.caucho.hessian.io.Hessian2Input.error(Hessian2Input.java:2720) ~[dubbo-2.8.4a.jar:2.8.4a] at com.alibaba.com.caucho.hessian.io.Hessian2Input.expect(Hessian2Input.java:2691) ~[dubbo-2.8.4a.jar:2.8.4a] at com.alibaba.com.caucho.hessian.io.Hessian2Input.readInt(Hessian2Input.java:773) ~[dubbo-2.8.4a.jar:2.8.4a] at com.alibaba.dubbo.common.serialize.support.hessian.Hessian2ObjectInput.readInt(Hessian2ObjectInput.java:58) ~[dubbo-2.8.4a.jar:2.8.4a] at com.alibaba.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation.decode(DecodeableRpcInvocation.java:106) ~[dubbo-2.8.4a.jar:2.8.4a]显然，因为版本差异造成了向下兼容有问题，那怎么办呢，我首先想到的是把消费端的dubbo starter也升级到2.8.4，但这个版本不是阿里做的，所以阿里官方的starter还是稳稳的停留在2.0.0的最新版本，只支持dubbo 2.6.0的版本，那怎么办呢？
2、看山不是山，回归传统，不用starter我其实首先尝试的是starter直接强行引用2.8.4的版本
<dependency> <groupId>com.alibaba.spring.boot</groupId> <artifactId>dubbo-spring-boot-starter</artifactId> <version>2.0.0</version> <exclusions> <exclusion> <groupId>com.alibaba</groupId> <artifactId>dubbo</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>dubbo</artifactId> <version>2.8.4</version> </dependency>可惜可耻的失败了，启动消费端的时候就报错了
12:12:01.733 [main] ERROR org.springframework.boot.SpringApplication - Application run failed java.lang.NoClassDefFoundError: com/alibaba/dubbo/qos/server/DubboLogo at com.alibaba.dubbo.spring.boot.context.event.DubboBannerApplicationListener.buildBannerText(DubboBannerApplicationListener.java:49) at com.alibaba.dubbo.spring.boot.context.event.DubboBannerApplicationListener.onApplicationEvent(DubboBannerApplicationListener.java:39) at com.alibaba.dubbo.spring.boot.context.event.DubboBannerApplicationListener.onApplicationEvent(DubboBannerApplicationListener.java:23) at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172) at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165) at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127) at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:76) at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:53) at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:345) at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) at com.skyblue.dubbodemo.DubbodemoClientApplication.main(DubbodemoClientApplication.java:13)