ClassNotFoundException issue in Maven project

Question

I was assigned to complete a project as part of my application for a job. The company send me to install the following requirements:

• OpenJDK 1.8
• Maven 3.x
• Git 2.x
• MySQL 5.x.

I am trying to run the app from the server side (java) and it throws this exception (probably a dependency issue but i can't find it):

2020-08-30 07:34:56.850 ERROR org.springframework.boot.SpringApplication:858 - Application run failed java.lang.NoClassDefFoundError: org/springframework/boot/bind/RelaxedDataBinder at org.springframework.boot.autoconfigure.EnableAutoConfigurationImportSelector.getExcludeAutoConfigurationsProperty(EnableAutoConfigurationImportSelector.java:179) at org.springframework.boot.autoconfigure.EnableAutoConfigurationImportSelector.getExclusions(EnableAutoConfigurationImportSelector.java:172) at org.springframework.boot.autoconfigure.EnableAutoConfigurationImportSelector.selectImports(EnableAutoConfigurationImportSelector.java:87) at org.springframework.context.annotation.ConfigurationClassParser$DefaultDeferredImportSelectorGroup.process(ConfigurationClassParser.java:892) at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGrouping.getImports(ConfigurationClassParser.java:878) at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGroupingHandler.processGroupImports(ConfigurationClassParser.java:804) at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorHandler.process(ConfigurationClassParser.java:774) at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:185) at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:315) at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:232) at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:275) at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:95) at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:705) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:531) at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) at gr.publicsoft.springbootcrud.Application.main(Application.java:12) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) Caused by: java.lang.ClassNotFoundException: org.springframework.boot.bind.RelaxedDataBinder at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581) at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522) ... 26 common frames omitted

**Pom.xml(general in project)**
<?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>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.4.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<groupId>gr.publicsoft.springbootcrud</groupId>
<artifactId>spring-boot-crud</artifactId>
<packaging>pom</packaging>
<version>1.0-SNAPSHOT</version>

<properties>
    <java.version>1.8</java.version>
</properties>

<modules>
    <module>springbootcrud-domain</module>
    <module>springbootcrud-service</module>
    <module>springbootcrud-webapp</module>
</modules>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
    </plugins>
</build>

</project>

**Pom.xml(inside app folder)**
<?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">
<parent>
    <artifactId>spring-boot-crud</artifactId>
    <groupId>gr.publicsoft.springbootcrud</groupId>
    <version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>

<artifactId>springbootcrud-webapp</artifactId>



<properties>
    <java.version>1.8</java.version>
    <finalName>${project.artifactId}-${project.version}</finalName>
</properties>

<profiles>
    <profile>
        <id>dev</id>
        <activation>
            <activeByDefault>true</activeByDefault>
        </activation>
    </profile>
</profiles>

<dependencies>

    <dependency>
        <groupId>gr.publicsoft.springbootcrud</groupId>
        <artifactId>springbootcrud-service</artifactId>
        <version>${project.parent.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-rest</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.liquibase</groupId>
        <artifactId>liquibase-core</artifactId>
    </dependency>
    <dependency>
        <groupId>eu.bitwalker</groupId>
        <artifactId>UserAgentUtils</artifactId>
        <version>1.21</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-autoconfigure</artifactId>
        <version>1.4.1.RELEASE</version>
    </dependency>
</dependencies>

<build>
    <finalName>${finalName}</finalName>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <executable>true</executable>
            </configuration>
        </plugin>
    </plugins>
</build>

</project>

Answer 1

Actually the spring-boot-starter-parent contain spring-boot-autoconfigure,see https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-parent/2.3.3.RELEASE for Managed Dependencies .

If you specify this version specifically (that is, there are two different versions), an error may occur.