No provider available from registry localhost:2181 for service com.alibaba.dubbo.demo.DemoService on consumer 192.168.60.253 use dubbo version 2.6.1, please check status of providers(disabled, not registered or in blacklist).
这个错误是你的提供者没有启动起来。也就是你的server端没有启动。请检查是否在Tomcat中启动失败.