Why "Blocked mirror for repositories" error though using HTTPS URL in maven settings.xml - maven-3

Question

my maven version is 3.8.5, and the following is mirrors config in maven settings.xml
<mirrors>
<mirror>
<id>aliyun</id>
<mirrorOf>*</mirrorOf>
<name>aliyun</name>
<url>https://maven.aliyun.com/nexus/content/groups/public/</url>
<blocked>true</blocked>
</mirror>
</mirrors>
When blocked set false , mvn packge running ok, but it set true , then output following error
[INFO] Scanning for projects...
[ERROR] [ERROR] Some problems were encountered while processing the POMs:
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. # line 209, column 21
[ERROR] Non-resolvable import POM: Could not transfer artifact org.springframework.security:spring-security-bom:pom:5.6.3 from/to aliyun (https://maven.aliyun.com/nexus/content/groups/public/): Blocked mirror for repositories: [central (https://repo.maven.apache.org/maven2, default, releases)] # org.springframework.boot:spring-boot-dependencies:2.6.7, /data/mvn/repository/org/springframework/boot/spring-boot-dependencies/2.6.7/spring-boot-dependencies-2.6.7.pom, line 2751, column 19
[ERROR] Non-resolvable import POM: Could not transfer artifact org.springframework.session:spring-session-bom:pom:2021.1.3 from/to aliyun (https://maven.aliyun.com/nexus/content/groups/public/): Blocked mirror for repositories: [central (https://repo.maven.apache.org/maven2, default, releases)] # org.springframework.boot:spring-boot-dependencies:2.6.7, /data/mvn/repository/org/springframework/boot/spring-boot-dependencies/2.6.7/spring-boot-dependencies-2.6.7.pom, line 2758, column 19
#
[ERROR] The build could not read 1 project -> [Help 1]
[ERROR]
[ERROR] The project com.adwetec:adwetec:1.0 (/data/adwetec-user/adwetec-idm/pom.xml) has 2 errors
[ERROR] Non-resolvable import POM: Could not transfer artifact org.springframework.security:spring-security-bom:pom:5.6.3 from/to aliyun (https://maven.aliyun.com/nexus/content/groups/public/): Blocked mirror for repositories: [central (https://repo.maven.apache.org/maven2, default, releases)] # org.springframework.boot:spring-boot-dependencies:2.6.7, /data/mvn/repository/org/springframework/boot/spring-boot-dependencies/2.6.7/spring-boot-dependencies-2.6.7.pom, line 2751, column 19 -> [Help 2]
[ERROR] Non-resolvable import POM: Could not transfer artifact org.springframework.session:spring-session-bom:pom:2021.1.3 from/to aliyun (https://maven.aliyun.com/nexus/content/groups/public/): Blocked mirror for repositories: [central (https://repo.maven.apache.org/maven2, default, releases)] # org.springframework.boot:spring-boot-dependencies:2.6.7, /data/mvn/repository/org/springframework/boot/spring-boot-dependencies/2.6.7/spring-boot-dependencies-2.6.7.pom, line 2758, column 19 -> [Help 2]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/ProjectBuildingException
[ERROR] [Help 2] http://cwiki.apache.org/confluence/display/MAVEN/UnresolvableModelException
WHY？How to set it ?

Answer 1

You have to configure the central access in your settings.xml correctly like this:
<profiles>
<profile>
<id>nexus</id>
<!--Enable snapshots for the built in central repo to direct -->
<!--all requests to nexus via the mirror -->
<repositories>
<repository>
<id>central</id>
<url>https://central</url>
<releases>
<enabled>true</enabled>
<checksumPolicy>fail</checksumPolicy>
</releases>
<snapshots>
<enabled>true</enabled>
<checksumPolicy>fail</checksumPolicy>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>central</id>
<url>https://central</url>
<releases>
<enabled>true</enabled>
<checksumPolicy>fail</checksumPolicy>
</releases>
<snapshots>
<enabled>true</enabled>
<checksumPolicy>fail</checksumPolicy>
</snapshots>
</pluginRepository>
</pluginRepositories>
</profile>
<activeProfiles>
<activeProfile>nexus</activeProfile>
</activeProfiles>