2021-08-13 19:05:22.766 ERROR 40484 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: org/springframework/core/metrics/ApplicationStartup
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:184) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:122) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.boot.SpringApplication.createApplicationContext(SpringApplication.java:607) [spring-boot-2.1.5.RELEASE.jar:2.1.5.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:310) [spring-boot-2.1.5.RELEASE.jar:2.1.5.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.5.RELEASE.jar:2.1.5.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.5.RELEASE.jar:2.1.5.RELEASE]
	at com.itheima.admin.AdminApplication.main(AdminApplication.java:14) [classes/:na]
Caused by: java.lang.NoClassDefFoundError: org/springframework/core/metrics/ApplicationStartup
	at org.springframework.context.support.AbstractApplicationContext.<init>(AbstractApplicationContext.java:229) ~[spring-context-5.3.8.jar:5.3.8]
	at org.springframework.context.support.GenericApplicationContext.<init>(GenericApplicationContext.java:112) ~[spring-context-5.3.8.jar:5.3.8]
	at org.springframework.web.context.support.GenericWebApplicationContext.<init>(GenericWebApplicationContext.java:81) ~[spring-web-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.<init>(ServletWebServerApplicationContext.java:115) ~[spring-boot-2.1.5.RELEASE.jar:2.1.5.RELEASE]
	at org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext.<init>(AnnotationConfigServletWebServerApplicationContext.java:72) ~[spring-boot-2.1.5.RELEASE.jar:2.1.5.RELEASE]
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_162]
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_162]
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_162]
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_162]
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:172) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	... 6 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.core.metrics.ApplicationStartup
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_162]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_162]
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338) ~[na:1.8.0_162]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_162]
	... 16 common frames omitted

报错环境：

Springcloud微服务架构中其中一个模块报错 org.springframework.core.metrics.ApplicationStartup

解决过程： 根据ApplicationStartup 类搜索，发现是

package org.springframework.context; 包下爆出的错误。

看了一下pom文件，有一个

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>5.3.8</version>
</dependency> 的包

 看了一下pom文件依赖， 猜测可能是版本的问题。别的地方依赖了5.1.7，又导入了一个定义为

5.3.8   .  删除  spring-context  依赖 ，问题解决。或者版本改为5.1.7