title: How do I see why a Jenkins build failed?
body: <p>I am trying to create my first Jenkins build job on a new Jenkins server. On the first two attempts the job failed; after I fixed those problems, the next build (which I requested manually by clicking "build now") failed - but there was no build error given.</p>
  
  <p>The only useful information I see is "No changes" (and a mercurial revision ID) on the build status page.</p>
  
  <p>How can I see why the build failed?</p>