Non-resolvable parent POM

Hi
I wrote a gitlab-ci for my project.
When I run the pipeline, I face this error:

[FATAL] Non-resolvable parent POM for [projectName]-parent:0.0.1-SNAPSHOT: Could not transfer artifact org.springframework.boot:spring-boot-starter-parent:pom:2.4.0 from/to [serverName]: Authentication failed for [serverName]/org/springframework/boot/spring-boot-starter-parent/2.4.0/spring-boot-starter-parent-2.4.0.pom 401 Unauthorized and 'parent.relativePath' points at no local POM @ line 6, column 13

The sixth line for my pom file starts at:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.4.0</version>
    <relativePath/>
</parent>

how can I solve this error?