After installing mvn and playing with the environment variables, the following error occurs when I run mvn help:system in cmd.

The configuration file has only been modified in two places, and there is no error in the repository location.

So the only thing that is wrong is the configuration of the place where you went to download

In the configuration file, so that no errors are reported

<mirror>
<id>mirrorId</id>
<mirrorOf>*</mirrorOf>
<name>Human Readable Name for this Mirror.</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
</mirror>