title: Failed to get bootstrap index from server
body: <p>I am trying to do code analysis for sonarqube. However, I got the error when running </p>
  
  <blockquote>
    <p>mvm sonar:sonar</p>
  </blockquote>
  
  <p>This is the error message:</p>
  
  <pre><code>[ERROR] SonarQube server [http://localhost:9000] can not be reached
  [INFO] ------------------------------------------------------------------------
  [INFO] BUILD FAILURE
  [INFO] ------------------------------------------------------------------------
  [INFO] Total time: 42.972 s
  [INFO] Finished at: 2017-06-06T08:51:52+08:00
  [INFO] Final Memory: 8M/19M
  [INFO] ------------------------------------------------------------------------
  [ERROR] Failed to execute goal org.sonarsource.scanner.maven:sonar-maven-plugin:
  3.3.0.603:sonar (default-cli) on project example-java-maven: Unable to execute SonarQube: 
  Fail to get bootstrap index from server: Status returned by url 
  [http://localhost:9000/batch/index] is not valid: [504] -&gt; [Help 1]
  [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/MojoExecutionException
  </code></pre>
  
  <p>But when I access <a href="http://localhost:9000" rel="noreferrer">http://localhost:9000</a> via the browser, I can see the sonarqube homepage.</p>
  
  <p>So why could this be happening?</p>
  
  <p>Thank you.</p>