报错内容：

org.apache.catalina.LifecycleException: Protocol handler start failed

org.apache.catalina.LifecycleException: Protocol handler start failed

at org.apache.catalina.connector.Connector.startInternal(Connector.java:1008) ~[tomcat-embed-core-9.0.17.jar:9.0.17]

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.17.jar:9.0.17]

at org.apache.catalina.core.StandardService.addConnector(StandardService.java:226) [tomcat-embed-core-9.0.17.jar:9.0.17]

at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.addPreviouslyRemovedConnectors(TomcatWebServer.java:259) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.start(TomcatWebServer.java:197) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.startWebServer(ServletWebServerApplicationContext.java:311) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:164) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:552) [spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]

at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]

at com.example.SpringcloudApplication.main(SpringcloudApplication.java:11) [classes/:na]

可能原因：端口号占用

处理方法：1 修改端口号

2 关闭占用的端口号

关闭方法

如果在win系统中运行，可以进入命令提示符  win+r  输入cmd即可进入

例如你的端口号是8080，可以使用以下命令进行查看是否为端口占用(如果未占用，就是其他问题，不是端口问题，可能是配置文件不对)

netstat -ano|findstr "8081" (win)        netstat -tunpl |grep 8081(luinx查看端口命令)

以上显示是8081被占用，进程号为 3080

使用以下语句关闭进程

taskkill -f -pid 3080 (win)      kill -9 3080  (luinx杀死进程命令)

重新启动项目即可

来源：oschina

链接：https://my.oschina.net/u/4185276/blog/3229778