GAE - ClassNotFoundException after deployment to Appspot server

Question

I've got the Google's example Guestbook project created using Maven's archetype com.google.appengine.archetypes:guestbook-archetype. When I run it locally using mvn appengine:devserver it works alright, the problems start when I try to deploy it on Google's Appspot. I get the following message:

Error: Server Error

The server encountered an error and could not complete your request.
If the problem persists, please report your problem and mention this error message and the query that caused it.

In the logs I can see this:

2013-05-01 05:38:28.356 / 500 3166ms 0kb Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.63 Safari/537.31
2001:6d8:10:a014:5176:bdbe:c152:53c0 - - [01/May/2013:05:38:28 -0700] "GET / HTTP/1.1" 500 0 - "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.63 Safari/537.31" "aghinzop.appspot.com" ms=3167 cpu_ms=2100 loading_request=1 app_engine_release=1.7.7 instance=00c61b117cdf51947e909cbfaf52e1739a7f4c
W 2013-05-01 05:38:28.325
EXCEPTION 
java.lang.ClassNotFoundException: ioserv.ioserv.SignGuestbookServlet
    at com.google.appengine.runtime.Request.process-53e8711216f37199(Request.java)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:359)
    at org.mortbay.util.Loader.loadClass(Loader.java:91)
    at org.mortbay.util.Loader.loadClass(Loader.java:71)
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:480)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:487)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:774)
    at com.google.tracing.TraceContext$DoInTraceContext.runInContext(TraceContext.java:751)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:342)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:334)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:484)
    at java.lang.Thread.run(Thread.java:722)
E 2013-05-01 05:38:28.326
javax.servlet.ServletContext log: unavailable
javax.servlet.UnavailableException: ioserv.ioserv.SignGuestbookServlet
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:79)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:219)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:438)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:480)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:487)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:774)
    at com.google.tracing.TraceContext$DoInTraceContext.runInContext(TraceContext.java:751)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:342)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:334)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:484)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:722)
W 2013-05-01 05:38:28.338
Failed startup of context com.google.apphosting.utils.jetty.RuntimeAppEngineWebAppContext@11c3e97{/,/base/data/home/apps/s~aghinzop/1.367061823227494749}
java.lang.NullPointerException
    at java.lang.Class.isAssignableFrom(Native Method)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:256)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:219)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:438)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:480)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:487)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:774)
    at com.google.tracing.TraceContext$DoInTraceContext.runInContext(TraceContext.java:751)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:342)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:334)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:484)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:722)
C 2013-05-01 05:38:28.342
Uncaught exception from servlet
javax.servlet.UnavailableException: Initialization failed.
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:228)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:438)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:480)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:487)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:774)
    at com.google.tracing.TraceContext$DoInTraceContext.runInContext(TraceContext.java:751)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:342)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:334)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:484)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:722)
I 2013-05-01 05:38:28.355
This request caused a new process to be started for your application, and thus caused your application code to be loaded for the first time. This request may thus take longer and use more CPU than a typical request for your application.

Here are the basic settings I have in Eclipse and the deployment log (I use App Engine Eclipse Plugin).

I'm not sure what "disabled because this is a Maven project" means here. Could you explain? And should I check this box?

The App Engine SDK selected here is the one provided by the Eclipse Plugin.

Here are the libs provided by plugin. There are also some Maven libs added by the archetype.

And here are the libs in WEB-INF/lib. I can see that there are very few of them and I realize that something may be missing. The problem is when I try to copy libs into this folder I get Cannot paste the clipboard contents into the selected elements. How can I do this? In a normal Dynamic Web Project (using this facet) it's as easy as Properties>Deployment Assembly>Add but here I have no clue how to do this.

I'd really appreciate your help! Thank you!

Answer 1

I'm not sure what "disabled because this is a Maven project" means here. Could you explain? And should I check this box?

There are two ways to manage your application (specifically web folder), one letting maven do it, and other letting google eclipse plugin do it. Since your application is built by maven, default assumption is your web app management is done by maven itself, so google eclipse plugin has disabled it by default. unless you are not removing maven, it should be as it is.

Coming to error, my guess is, though you are building and testing through maven, you might be trying to deploy through eclipse, please try mvn appengine:update and it should work.

hope it helps.