Google App Engine fails to launch in Eclipse

Question

I'm having trouble launching Google App Engine in eclipse.

I created a new "Maven-based Google App Engine Standard Java Project" with the Google Cloud Tools plugin for Eclipse by selecting the "Hello World template".

I then tried to launch the application by right-clicking on the project in the Package Explorer, and choosing the option "Run As > App Engine".

The application fails to launch. The following stack trace appears in the Error Log:

java.lang.NullPointerException
    at com.google.cloud.tools.eclipse.appengine.localserver.launching.LaunchHelper.findExistingServers(LaunchHelper.java:110)
    at com.google.cloud.tools.eclipse.appengine.localserver.launching.LaunchHelper.launch(LaunchHelper.java:61)
    at com.google.cloud.tools.eclipse.appengine.localserver.launching.LocalAppEngineStandardLaunchShortcut.launch(LocalAppEngineStandardLaunchShortcut.java:44)
    at org.eclipse.debug.internal.ui.launchConfigurations.LaunchShortcutExtension.launch(LaunchShortcutExtension.java:431)
    at org.eclipse.debug.internal.ui.actions.LaunchShortcutAction.run(LaunchShortcutAction.java:74)
    at org.eclipse.debug.internal.ui.actions.LaunchShortcutAction.runWithEvent(LaunchShortcutAction.java:123)
    at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:595)
    at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:511)
    at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:420)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4362)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1113)

Here's my session data:

eclipse.buildId=4.5.2.M20160212-1500
java.version=1.8.0_111
java.vendor=Oracle Corporation

What am I missing? Is another step required to get the application to launch successfully?

Answer 1

NPEs should never happen, and from looking at the code, it would seem that you have a corrupt server definition. You could open the Servers view and remove any corrupt servers and then try again.

But before doing so, if you wouldn't mind, we would first appreciate you providing more details on this GitHub issue to include your .../.metadata/.plugins/org.eclipse.wst.server.core/servers.xml file, the screenshot of the Servers view, and the exact steps to reproduce, so that we can fix it.