java.lang.NoClassDefFoundError: org/springframework/core/env/ConfigurableEnvironment

Recommended Approach

1. Go to Spring boot Initialzr site and select web stack as a dependency as shown in below .
2. As Spring Boot uses the concept of Opinionated dependencies and Bill of Materials, It will automatically pull the other dependencies and resolve your classNotFoundException issue. And in your case it misses out the Spring-core-4.2.4.RELEASE.jar dependency.

3. Execute the Maven Goal as clean install spring-boot:run -e and you can find your maven dependencies in your IDE and below given is a sample POM 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>
   
      <groupId>com.example</groupId>
     <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
   
        <name>demo</name>
       <description>Demo project for Spring Boot</description>
   
        <parent>
          <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
      </parent>
   
       <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
          <project.reporting.outputEncoding>UTF-       8</project.reporting.outputEncoding>
       <java.version>1.8</java.version>
       </properties>
   
    <dependencies>
        <dependency>
          <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
   
        <dependency>
             <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-tomcat</artifactId>
                <scope>provided</scope>
         </dependency>
       <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-test</artifactId>
           <scope>test</scope>
         < /dependency>
       </dependencies>
   
     <build>
       <finalName>demo</finalName>
          <plugins>
            <plugin>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
         </plugins>
       </build>
   

Spring boot is running -

<spring.version>4.3.2.RELEASE</spring.version>

For -

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>1.4.0.RELEASE</version>
    </dependency>

While you are importing -

    <springframework.version>4.3.0.RELEASE</springframework.version>

You can confirm on the master pom -

https://github.com/spring-projects/spring-boot/blob/v1.4.0.RELEASE/spring-boot-dependencies/pom.xml

Can you update the spring version in your pom? Or deal with managing maven dependencies