Can't start google web app in eclipse, Security restrictions will not be completely emulated

Question

When I try to run the auto generated code in my google web app project using GAE I get the following error:

Mar 19, 2014 5:21:28 PM com.google.appengine.tools.development.agent.AppEngineDevAgent premain SEVERE: Unable to load the App Engine dev agent. Security restrictions will not be completely emulated. java.lang.RuntimeException: Unexpected exception during cast. at com.google.apphosting.utils.clearcast.ClearCast$CasterImpl.cast(ClearCast.java:385) at com.google.apphosting.utils.clearcast.ClearCast.staticCast(ClearCast.java:252) at com.google.apphosting.utils.clearcast.ClearCast.staticCast(ClearCast.java:263) at com.google.appengine.tools.development.agent.AppEngineDevAgent.premain(AppEngineDevAgent.java:61) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at sun.instrument.InstrumentationImpl.loadClassAndStartAgent(Unknown Source) at sun.instrument.InstrumentationImpl.loadClassAndCallPremain(Unknown Source) Caused by: java.lang.IllegalAccessException: Class com.google.apphosting.utils.clearcast.ClearCast$CasterImpl can not access a member of class com.google.appengine.tools.development.agent.$Proxy0 with modifiers "public" at sun.reflect.Reflection.ensureMemberAccess(Unknown Source) at java.lang.reflect.AccessibleObject.slowCheckMemberAccess(Unknown Source) at java.lang.reflect.AccessibleObject.checkAccess(Unknown Source) at java.lang.reflect.Constructor.newInstance(Unknown Source) at com.google.apphosting.utils.clearcast.ClearCast$CasterImpl.cast(ClearCast.java:383) ... 9 more 

Does anyone have any clue how to fix this?

Code:

@SuppressWarnings("serial") public class Lab7Servlet extends HttpServlet {     public void doGet(HttpServletRequest req, HttpServletResponse resp)         throws IOException {     resp.setContentType("text/plain");     resp.getWriter().println("Hello, world");     } } 

Answer 1

iQue,

I encountered exactly the same problem, and I discovered that my eclipse was using JRE 8 (version 1.8). I didn't intend this, and when I changed it to 1.7, this solved the problem.

Edit: Window -> Preferences -> Java -> Installed JREs. Checked jre7 to make it default.

Relevant note: The App Engine installation instructions say to use 1.7 (but don't say you can't use 1.8): https://developers.google.com/appengine/docs/java/gettingstarted/installing