title: IntelliJ: Error: java: release version 10 not supported
body: <p>In IntelliJ, I'm getting this strange error message when I try to build from the build menu</p>
  <blockquote>
  <p>Error: java: release version 10 not supported</p>
  </blockquote>
  <p>I don't understand this, since in <em>Project Structure</em>, I have these settings set:</p>
  <blockquote>
  <p>Project SDK: 9.0<br />
  Project Language Level: SDK Default<br />
  Module Language Level: Project Default (both modules)</p>
  </blockquote>
  <p>In my pom.xml files, I have these properties set in both modules:</p>
  <pre><code>&lt;maven.compiler.source&gt;9&lt;/maven.compiler.source&gt;
  &lt;maven.compiler.target&gt;9&lt;/maven.compiler.target&gt;
  </code></pre>
  <p>I have no idea why it's trying to use JDK 10 for anything, but I still get that message.</p>
  <p>I'd be happy to use JDK 10, but my project doesn't work in that version, so I'm going back to see which versions it works in. I have SDKs installed for version 1.4 through 10.</p>
  <p>I've also tried building using JDK 1.8, but I get a slightly different error message:</p>
  <blockquote>
  <p>Error: java: invalid target release: 10</p>
  </blockquote>
  <p>I've found that I can build from the command line using JDK 9, but I need to build from my IDE.</p>
  <p>Can anyone tell me how to build my project using JDK 1.9 or 1.8?</p>