title: Any Other Reasons for Maven "Failed to retrieve plugin descriptor" Besides Proxy
body: <p>This error in other posts I'm told is a result of the proxy not being set up properly</p>
  
  <p>however I do have our proxy set up correctly in settings.xml (we don't have user/password)</p>
  
  <p>Is there any other cause for this maven error ?</p>
  
  <pre><code>i.e.: 
  
  
    .m2&gt;
  
  &lt;settings&gt;
    &lt;proxies&gt;
     &lt;proxy&gt;
        &lt;active&gt;true&lt;/active&gt;
        &lt;protocol&gt;http&lt;/protocol&gt;
        &lt;host&gt;proxy.ours.net&lt;/host&gt;
        &lt;port&gt;8080&lt;/port&gt;
      &lt;/proxy&gt;
    &lt;/proxies&gt;
  &lt;/settings&gt;
  
  
   C:&gt;mvn archetype:generate -DgroupId=com.mycompany
  .app -DartifactId=my-app -DarchetypeArtifactId=maven-archetype-quickstart -Dinte
  ractiveMode=false
  [INFO] Scanning for projects...
  Downloading: http://uk.maven.org/maven2/org/apache/maven/plugins/maven-clean-plu
  gin/2.5/maven-clean-plugin-2.5.pom
  [WARNING] Failed to retrieve plugin descriptor for org.apache.maven.plugins:mave
  n-clean-plugin:2.5: Plugin org.apache.maven.plugins:maven-clean-plugin:2.5 or on
  e of its dependencies could not be resolved: Failed to read artifact descriptor
  for org.apache.maven.plugins:maven-clean-plugin:jar:2.5
  Downloading: http://uk.maven.org/maven2/org/apache/maven/plugins/maven-install-p
  lugin/2.4/maven-install-plugin-2.4.pom
  
  etc
  
         [WARNING] Failure to transfer org.codehaus.mojo/maven-metadata.xml from http://u
  k.maven.org/maven2 was cached in the local repository, resolution will not be re
  attempted until the update interval of UK has elapsed or updates are forced. Ori
  ginal error: Could not transfer metadata org.codehaus.mojo/maven-metadata.xml fr
  om/to UK (http://uk.maven.org/maven2): Not authorized by proxy , ReasonPhrase:Pr
  oxy Authentication Required.
  [INFO] ------------------------------------------------------------------------
  [INFO] BUILD FAILURE
  </code></pre>