title: java.lang.UnsupportedClassVersionError in Google App Engine
body: <p>I'm running windows 7 and juno. Jdk 1.7, gwt 2.4, app engine 1.7. </p>
  
  <p>I did the stockwatcher tutorial <a href="https://developers.google.com/web-toolkit/doc/latest/tutorial/gettingstarted" rel="nofollow noreferrer">here</a> and everything worked great. I then deployed it to app engine. Everything still worked great!</p>
  
  <p>However, I then did the RPC part of the tutorial <a href="https://developers.google.com/web-toolkit/doc/latest/tutorial/RPC" rel="nofollow noreferrer">here</a>. When I ran locally, I got a java.lang.VerifyError that I fixed by following <a href="https://stackoverflow.com/questions/7970622/java-7-jvm-verifyerror-in-eclipse">this</a> thread (putting -XX:-UseSplitVerifier in default VM arguments).  It then worked locally and I deployed to app engine.</p>
  
  <p>In app engine, I get a java.lang.UpsupportedClassVersionError.  I found two threads that seem to have the same problem, <a href="https://stackoverflow.com/questions/8139477/google-app-engine-and-java-version">here</a> and <a href="https://stackoverflow.com/questions/8568083/java-lang-unsupportedclassversionerror-com-google-mystorage-server-greetingserv">here</a>. I'm using a fresh install of windows 7 and the only jdk I downloaded was 1.7. Looking through eclipse, I see jre7, jdk 1.7, and app engine 1.7.  </p>
  
  <p>I read somewhere that app engine doesn't work with 1.7. However the app engine sdk version on the downloads page is 1.7 (I think that might be super recent) but I don't really know if those things are related.  I went ahead and downloaded java 6 and app engine sdk 1.6.6, added jre6 to the installed jres, set the compiler compliance level to 1.6, changed it in my project too for good measure, and changed the default app engine sdk to 1.6.6.</p>
  
  <p>Now I'm getting the error, "Java compiler level does not match the version of the installed java project facet." I googled the problem and everyone says to right click the project and change the facet, but I can't seem to find that option. I also have no idea if I'm going about this the right way. I'd much rather use the most recent versions of everything if possible. I also don't understand why app engine worked the first time with no RPC, but broke with the RPC.</p>
  
  <p>Any help would be greatly appreciated!!! THANK YOU!!!</p>