Non-resolvable import POM Failure to find

The version 2.0.0.M6 isn't located in the repo http://repo.maven.apache.org/maven2. If you wan't to use this version you have to use the maven repo http://repo.spring.io/milestone. So add it to your POM file:

<repositories>
    <repository>
        <id>spring-milestone-repo</id>
        <url>http://repo.spring.io/milestone/</url>
    </repository>
</repositories>

I would recommend you to use the latest release version of spring-boot (1.5.8.RELEASE), not a milestone version. I don't know how your POM looks like, but you can define spring boot in your POM in different ways:

1. Using the Spring Boot parent POM

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.8.RELEASE</version>
</parent>

Then you can add the dependencies you wish to use e.g.:

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

See: https://spring.io/guides/gs/spring-boot/

2. Declare Spring-Boot in Dependency-Management

If you already using an own parent POM, you could also import the spring boot dependency management in your POM:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>1.5.8.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

Same as in variant #1 you can declare afterwards the dependencies of spring boot you wish to use.