Non-resolvable parent POM in SpringBoot

This may be because of spring initializer created project pom file like this

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent> 

However, sts is compatible with version "2.0.4.RELEASE", just make this change

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent> 

further Maven -> Update Project

From where revision will be replaced ?

Modify pom.xml by specifying any version like below.

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

Solved the issue. There was a little mistake. It should be 1.4.2.RELEASE instead of 1.4.2 RELEASE. There should not be space between RELEASE and 2. This little dot was causing the issue.