Spring boot 2.3.3.RELEASE project fails build with exception “org.gradle.api.plugins.UnknownPluginException” in gradle version 5.6.3

my gradle version is 5.6.3.

while I run a spring boot project of 2.3.3.RELEASE with ‘gradle clean build’ it shows me following error:

* What went wrong:
Plugin [id: 'org.springframework.boot', version: '2.3.3.RELEASE'] was not found in any of the following sources:

- Gradle Core Plugins (plugin is not in 'org.gradle' namespace)
- Plugin Repositories (could not resolve plugin artifact 'org.springframework.boot:org.springframework.boot.gradle.plugin:2.3.3.RELEASE')
  Searched in the following repositories:
    Gradle Central Plugin Repository

Updating my question:

my build.gradle :

plugins {
    id 'org.springframework.boot' version '2.3.3.RELEASE'
    id 'io.spring.dependency-management' version '1.0.10.RELEASE'
    id 'java'
    id 'war'
}

group = 'net.project'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web'
    developmentOnly 'org.springframework.boot:spring-boot-devtools'
    providedRuntime 'org.springframework.boot:spring-boot-starter-tomcat'

    testImplementation('org.springframework.boot:spring-boot-starter-test') {
        exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
    }

}

test {
    useJUnitPlatform()
}

and my settings.gradle contains just the root project name

Answer

Spring boot 2.3.3.RELEASE definitely exists on gradle central plugin repository as I can see here. You’re most probably building behind a corporate firewall with outgoing URL disabled. Had the same issue earlier, which I solved it by asking the IT Operations team(nicely) to allow https://plugins.gradle.org/ requests to go through. For security reasons if they don’t allow this then you can ask them to create a local mirror server as instructed here