Q:

i have errors when run spring boot project

I am beginer with java and Spring boot and when i build simple project and run it then i get errors about can not load main class but i don't why ?? somebody can help me?? Thank a lot!
Here my struct of my project: 
1
and my main class:
package app3;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class App3 {
    public static void main(String[] args) {
        SpringApplication.run(App3.class, args);
    }
}

my controller file
package app3;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

// Đánh dấu đây là một Controller
// Nơi tiếp nhận các reqquest từ phía người dùng
@Controller
public class WebController {

    // Đón nhận request GET
    @GetMapping("/") // Nếu người dùng request tới địa chỉ "/"
    public String index() {
        return "index"; // Trả về file index.html
    }
}

my XML file: 
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <packaging>pom</packaging>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.0.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>app3</groupId>
    <artifactId>spring-boot-learning</artifactId>
    <version>0.0.2-SNAPSHOT</version>
    <name>spring-boot-learning</name>
    <description>Everything about Spring Boot</description>

    <dependencies>

        <!--spring mvc, rest-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- thymeleaf -->
        <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>    
                <mainClass>app3.App3</mainClass>
            </configuration>
        </plugin>
        </plugins>
    </build>

</project>

and simple html file in reources dict  
then i type command  mvn spring-boot:run -e
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.google.inject.internal.cglib.core.$ReflectUtils$1 (file:/usr/share/maven/lib/guice.jar) to method java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain)
WARNING: Please consider reporting this to the maintainers of com.google.inject.internal.cglib.core.$ReflectUtils$1
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
[INFO] 
[INFO] ---------------------< app3:spring-boot-learning >----------------------
[INFO] Building spring-boot-learning 0.0.2-SNAPSHOT
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] >>> spring-boot-maven-plugin:2.2.0.RELEASE:run (default-cli) > test-compile @ spring-boot-learning >>>
[INFO] 
[INFO] <<< spring-boot-maven-plugin:2.2.0.RELEASE:run (default-cli) < test-compile @ spring-boot-learning <<<
[INFO] 
[INFO] 
[INFO] --- spring-boot-maven-plugin:2.2.0.RELEASE:run (default-cli) @ spring-boot-learning ---
[INFO] Attaching agents: []
Error: Could not find or load main class app3.App3
Caused by: java.lang.ClassNotFoundException: app3.App3
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.576 s
[INFO] Finished at: 2019-11-11T23:37:45+07:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.2.0.RELEASE:run (default-cli) on project spring-boot-learning: Application finished with exit code: 1 -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.2.0.RELEASE:run (default-cli) on project spring-boot-learning: Application finished with exit code: 1
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
Caused by: org.apache.maven.plugin.MojoExecutionException: Application finished with exit code: 1
    at org.springframework.boot.maven.RunMojo.runWithForkedJvm (RunMojo.java:108)
    at org.springframework.boot.maven.AbstractRunMojo.doRunWithForkedJvm (AbstractRunMojo.java:284)
    at org.springframework.boot.maven.AbstractRunMojo.run (AbstractRunMojo.java:249)
    at org.springframework.boot.maven.AbstractRunMojo.execute (AbstractRunMojo.java:205)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
[ERROR] 
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

when i type mvn clean spring-boot:start -e
i get the log:
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.google.inject.internal.cglib.core.$ReflectUtils$1 (file:/usr/share/maven/lib/guice.jar) to method java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain)
WARNING: Please consider reporting this to the maintainers of com.google.inject.internal.cglib.core.$ReflectUtils$1
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
[INFO] 
[INFO] ---------------------< app3:spring-boot-learning >----------------------
[INFO] Building spring-boot-learning 0.0.2-SNAPSHOT
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] --- maven-clean-plugin:3.1.0:clean (default-clean) @ spring-boot-learning ---
[INFO] 
[INFO] --- spring-boot-maven-plugin:2.2.0.RELEASE:start (default-cli) @ spring-boot-learning ---
[INFO] Attaching agents: []
Error: Could not find or load main class app3.App3
Caused by: java.lang.ClassNotFoundException: app3.App3
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.362 s
[INFO] Finished at: 2019-11-11T23:39:46+07:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.2.0.RELEASE:start (default-cli) on project spring-boot-learning: Could not contact Spring Boot application: Failed to retrieve RMIServer stub: javax.naming.CommunicationException [Root exception is java.rmi.ConnectIOException: error during JRMP connection establishment; nested exception is: 
[ERROR]         java.net.SocketException: Connection reset]
[ERROR] -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.2.0.RELEASE:start (default-cli) on project spring-boot-learning: Could not contact Spring Boot application
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
Caused by: org.apache.maven.plugin.MojoFailureException: Could not contact Spring Boot application
    at org.springframework.boot.maven.StartMojo.waitForSpringApplication (StartMojo.java:185)
    at org.springframework.boot.maven.StartMojo.runWithForkedJvm (StartMojo.java:96)
    at org.springframework.boot.maven.AbstractRunMojo.doRunWithForkedJvm (AbstractRunMojo.java:284)
    at org.springframework.boot.maven.AbstractRunMojo.run (AbstractRunMojo.java:249)
    at org.springframework.boot.maven.AbstractRunMojo.execute (AbstractRunMojo.java:205)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
Caused by: java.io.IOException: Failed to retrieve RMIServer stub: javax.naming.CommunicationException [Root exception is java.rmi.ConnectIOException: error during JRMP connection establishment; nested exception is: 
        java.net.SocketException: Connection reset]
    at javax.management.remote.rmi.RMIConnector.connect (RMIConnector.java:370)
    at javax.management.remote.JMXConnectorFactory.connect (JMXConnectorFactory.java:270)
    at org.springframework.boot.maven.SpringApplicationAdminClient.connect (SpringApplicationAdminClient.java:116)
    at org.springframework.boot.maven.StartMojo$CreateJmxConnector.call (StartMojo.java:271)
    at org.springframework.boot.maven.StartMojo$CreateJmxConnector.call (StartMojo.java:260)
    at org.springframework.boot.maven.StartMojo.execute (StartMojo.java:240)
    at org.springframework.boot.maven.StartMojo.waitForForkedSpringApplication (StartMojo.java:195)
    at org.springframework.boot.maven.StartMojo.waitForSpringApplication (StartMojo.java:178)
    at org.springframework.boot.maven.StartMojo.runWithForkedJvm (StartMojo.java:96)
    at org.springframework.boot.maven.AbstractRunMojo.doRunWithForkedJvm (AbstractRunMojo.java:284)
    at org.springframework.boot.maven.AbstractRunMojo.run (AbstractRunMojo.java:249)
    at org.springframework.boot.maven.AbstractRunMojo.execute (AbstractRunMojo.java:205)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)

    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
Caused by: javax.naming.CommunicationException
    at com.sun.jndi.rmi.registry.RegistryContext.lookup (RegistryContext.java:137)
    at com.sun.jndi.toolkit.url.GenericURLContext.lookup (GenericURLContext.java:207)
    at javax.naming.InitialContext.lookup (InitialContext.java:409)
    at javax.management.remote.rmi.RMIConnector.findRMIServerJNDI (RMIConnector.java:1839)

    at org.springframework.boot.maven.StartMojo$CreateJmxConnector.call (StartMojo.java:271)
    at org.springframework.boot.maven.StartMojo$CreateJmxConnector.call (StartMojo.java:260)
    at org.springframework.boot.maven.StartMojo.execute (StartMojo.java:240)
    at org.springframework.boot.maven.StartMojo.waitForForkedSpringApplication (StartMojo.java:195)
    at org.springframework.boot.maven.StartMojo.waitForSpringApplication (StartMojo.java:178)
    at org.springframework.boot.maven.StartMojo.runWithForkedJvm (StartMojo.java:96)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
Caused by: java.rmi.ConnectIOException: error during JRMP connection establishment; nested exception is: 
        java.net.SocketException: Connection reset
    at sun.rmi.transport.tcp.TCPChannel.createConnection (TCPChannel.java:300)
    at sun.rmi.transport.tcp.TCPChannel.newConnection (TCPChannel.java:196)
    at sun.rmi.server.UnicastRef.newCall (UnicastRef.java:338)
    at sun.rmi.registry.RegistryImpl_Stub.lookup (RegistryImpl_Stub.java:112)
    at com.sun.jndi.rmi.registry.RegistryContext.lookup (RegistryContext.java:133)
    at com.sun.jndi.toolkit.url.GenericURLContext.lookup (GenericURLContext.java:207)
    at javax.naming.InitialContext.lookup (InitialContext.java:409)
    at javax.management.remote.rmi.RMIConnector.findRMIServerJNDI (RMIConnector.java:1839)
    at javax.management.remote.rmi.RMIConnector.findRMIServer (RMIConnector.java:1813)
    at javax.management.remote.rmi.RMIConnector.connect (RMIConnector.java:302)
    at javax.management.remote.JMXConnectorFactory.connect (JMXConnectorFactory.java:270)
    at org.springframework.boot.maven.SpringApplicationAdminClient.connect (SpringApplicationAdminClient.java:116)
    at org.springframework.boot.maven.StartMojo$CreateJmxConnector.call (StartMojo.java:271)
    at org.springframework.boot.maven.StartMojo$CreateJmxConnector.call (StartMojo.java:260)
    at org.springframework.boot.maven.StartMojo.execute (StartMojo.java:240)
    at org.springframework.boot.maven.StartMojo.waitForForkedSpringApplication (StartMojo.java:195)
    at org.springframework.boot.maven.StartMojo.waitForSpringApplication (StartMojo.java:178)
    at org.springframework.boot.maven.StartMojo.runWithForkedJvm (StartMojo.java:96)
    at org.springframework.boot.maven.AbstractRunMojo.doRunWithForkedJvm (AbstractRunMojo.java:284)
    at org.springframework.boot.maven.AbstractRunMojo.run (AbstractRunMojo.java:249)
    at org.springframework.boot.maven.AbstractRunMojo.execute (AbstractRunMojo.java:205)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
Caused by: java.net.SocketException: Connection reset
    at java.net.SocketInputStream.read (SocketInputStream.java:186)
    at java.net.SocketInputStream.read (SocketInputStream.java:140)
    at java.io.BufferedInputStream.fill (BufferedInputStream.java:252)
    at java.io.BufferedInputStream.read (BufferedInputStream.java:271)
    at java.io.DataInputStream.readByte (DataInputStream.java:270)
    at sun.rmi.transport.tcp.TCPChannel.createConnection (TCPChannel.java:239)
    at sun.rmi.transport.tcp.TCPChannel.newConnection (TCPChannel.java:196)
    at sun.rmi.server.UnicastRef.newCall (UnicastRef.java:338)
    at sun.rmi.registry.RegistryImpl_Stub.lookup (RegistryImpl_Stub.java:112)
    at com.sun.jndi.rmi.registry.RegistryContext.lookup (RegistryContext.java:133)
    at com.sun.jndi.toolkit.url.GenericURLContext.lookup (GenericURLContext.java:207)
    at javax.naming.InitialContext.lookup (InitialContext.java:409)
    at javax.management.remote.rmi.RMIConnector.findRMIServerJNDI (RMIConnector.java:1839)
    at javax.management.remote.rmi.RMIConnector.findRMIServer (RMIConnector.java:1813)
    at javax.management.remote.rmi.RMIConnector.connect (RMIConnector.java:302)
    at javax.management.remote.JMXConnectorFactory.connect (JMXConnectorFactory.java:270)
    at org.springframework.boot.maven.SpringApplicationAdminClient.connect (SpringApplicationAdminClient.java:116)
    at org.springframework.boot.maven.StartMojo$CreateJmxConnector.call (StartMojo.java:271)
    at org.springframework.boot.maven.StartMojo$CreateJmxConnector.call (StartMojo.java:260)
    at org.springframework.boot.maven.StartMojo.execute (StartMojo.java:240)
    at org.springframework.boot.maven.StartMojo.waitForForkedSpringApplication (StartMojo.java:195)
    at org.springframework.boot.maven.StartMojo.waitForSpringApplication (StartMojo.java:178)
    at org.springframework.boot.maven.StartMojo.runWithForkedJvm (StartMojo.java:96)
    at org.springframework.boot.maven.AbstractRunMojo.doRunWithForkedJvm (AbstractRunMojo.java:284)
    at org.springframework.boot.maven.AbstractRunMojo.run (AbstractRunMojo.java:249)
    at org.springframework.boot.maven.AbstractRunMojo.execute (AbstractRunMojo.java:205)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
       at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
[ERROR] 
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

sombody can help me! thank a lot!

A:

remove the <packaging>pom</packaging> from your pom.xml and then run mvn clean install 
it should work

you have used packaging type pom, you should use the jar, The
  default packaging type is jar, If you don't have any it will use
  packaging as jar
The packaging type of a Maven project specifies the type of artifact
  the project produces. There are many built-in Maven packaging types
  (for example, jar, war, and ear).
A pom type is packaging a kind container of submodules, a submodule is
  represented by a subdirectory in the same directory 

