Error: java.lang.NoSuchMethodError: org.mortbay.thread.Timeout.

After installing the 2.1 GWT (google web toolkit) in Eclipse received the following error:

Exception in thread "main" java.lang.NoSuchMethodError: org.mortbay.thread.Timeout.(Ljava/lang/Object;)V

at org.mortbay.io.nio.SelectorManager$SelectSet.(SelectorManager.java:306)

at org.mortbay.io.nio.SelectorManager.doStart(SelectorManager.java:223)

at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)

at org.mortbay.jetty.nio.SelectChannelConnector.doStart(SelectChannelConnector.java:303)

at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)

at org.mortbay.jetty.Server.doStart(Server.java:233)

at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)

at com.google.gwt.dev.shell.jetty.JettyLauncher.start(JettyLauncher.java:542)

at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:431)

at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1053)

at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:795)

at com.google.gwt.dev.DevMode.main(DevMode.java:282)

This indicates duplicate libraries.

To solve:

In eclipse, Press CTRL + SHIFT + T and search for: org.mortbay.io.nio.SelectorManager

Probably you will find more than one reference.

In my environment were found two:

-> com.google.appengine.eclipse.sdkbundle.1.3.8_1.3.8.v201010161055

-> com.google.gwt.eclipse.sdkbundle.2.1.0_2.1.0.v201010280102

In Java:

- 50% of problems are classpath,

- the other 50% of the problems resides in your own code

- and the remaining 50% is with the user ;o)