I have weird null pointer exceptions when I remove projects. I always have several NPE, see logs below. event.getDelta() can return null for several cases, so I've added if(event.getDelta()!=null) every place where I saw NPE. And here is an issue http://jira.jboss.org/jira/browse/JBIDE-1238 !ENTRY org.eclipse.core.resources 4 2 2007-10-31 12:30:29.234 !MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.core.resources". !STACK 0 java.lang.NullPointerException at org.jboss.ide.eclipse.archives.core.WorkspaceChangeListener.resourceChanged(WorkspaceChangeListener.java:55) at org.eclipse.core.internal.events.NotificationManager$2.run(NotificationManager.java:282) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37) at org.eclipse.core.internal.events.NotificationManager.notify(NotificationManager.java:276) at org.eclipse.core.internal.events.NotificationManager.handleEvent(NotificationManager.java:260) at org.eclipse.core.internal.resources.Workspace.broadcastEvent(Workspace.java:305) at org.eclipse.core.internal.resources.Resource.unprotectedDelete(Resource.java:1662) at org.eclipse.core.internal.resources.Resource.delete(Resource.java:700) at org.eclipse.core.internal.resources.Project.delete(Project.java:289) at org.eclipse.ui.ide.undo.WorkspaceUndoUtil.delete(WorkspaceUndoUtil.java:578) at org.eclipse.ui.ide.undo.WorkspaceUndoUtil.delete(WorkspaceUndoUtil.java:172) at org.eclipse.ui.ide.undo.AbstractResourcesOperation.delete(AbstractResourcesOperation.java:111) at org.eclipse.ui.ide.undo.DeleteResourcesOperation.doExecute(DeleteResourcesOperation.java:67) at org.eclipse.ui.ide.undo.AbstractWorkspaceOperation$1.run(AbstractWorkspaceOperation.java:206) at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1797) at org.eclipse.ui.ide.undo.AbstractWorkspaceOperation.execute(AbstractWorkspaceOperation.java:204) at org.eclipse.ui.actions.DeleteResourceAction$4.run(DeleteResourceAction.java:533) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) !ENTRY org.eclipse.core.resources 4 2 2007-10-31 12:30:29.250 !MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.core.resources". !STACK 0 java.lang.NullPointerException at org.jboss.ide.eclipse.as.core.modules.SingleDeployableFactory$FileDeletionListener.resourceChanged(SingleDeployableFactory.java:257) at org.eclipse.core.internal.events.NotificationManager$2.run(NotificationManager.java:282) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37) at org.eclipse.core.internal.events.NotificationManager.notify(NotificationManager.java:276) at org.eclipse.core.internal.events.NotificationManager.handleEvent(NotificationManager.java:260) at org.eclipse.core.internal.resources.Workspace.broadcastEvent(Workspace.java:305) at org.eclipse.core.internal.resources.Resource.unprotectedDelete(Resource.java:1662) at org.eclipse.core.internal.resources.Resource.delete(Resource.java:700) at org.eclipse.core.internal.resources.Project.delete(Project.java:289) at org.eclipse.ui.ide.undo.WorkspaceUndoUtil.delete(WorkspaceUndoUtil.java:578) at org.eclipse.ui.ide.undo.WorkspaceUndoUtil.delete(WorkspaceUndoUtil.java:172) at org.eclipse.ui.ide.undo.AbstractResourcesOperation.delete(AbstractResourcesOperation.java:111) at org.eclipse.ui.ide.undo.DeleteResourcesOperation.doExecute(DeleteResourcesOperation.java:67) at org.eclipse.ui.ide.undo.AbstractWorkspaceOperation$1.run(AbstractWorkspaceOperation.java:206) at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1797) at org.eclipse.ui.ide.undo.AbstractWorkspaceOperation.execute(AbstractWorkspaceOperation.java:204) at org.eclipse.ui.actions.DeleteResourceAction$4.run(DeleteResourceAction.java:533) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) !ENTRY org.eclipse.core.resources 4 2 2007-10-31 12:30:29.375 !MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.core.resources". !STACK 0 java.lang.NullPointerException at org.jboss.ide.eclipse.archives.core.WorkspaceChangeListener.resourceChanged(WorkspaceChangeListener.java:55) at org.eclipse.core.internal.events.NotificationManager$2.run(NotificationManager.java:282) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37) at org.eclipse.core.internal.events.NotificationManager.notify(NotificationManager.java:276) at org.eclipse.core.internal.events.NotificationManager.handleEvent(NotificationManager.java:260) at org.eclipse.core.internal.resources.Workspace.broadcastEvent(Workspace.java:305) at org.eclipse.core.internal.resources.Resource.unprotectedDelete(Resource.java:1662) at org.eclipse.core.internal.resources.Resource.delete(Resource.java:700) at org.eclipse.core.internal.resources.Project.delete(Project.java:289) at org.eclipse.ui.ide.undo.WorkspaceUndoUtil.delete(WorkspaceUndoUtil.java:578) at org.eclipse.ui.ide.undo.WorkspaceUndoUtil.delete(WorkspaceUndoUtil.java:172) at org.eclipse.ui.ide.undo.AbstractResourcesOperation.delete(AbstractResourcesOperation.java:111) at org.eclipse.ui.ide.undo.DeleteResourcesOperation.doExecute(DeleteResourcesOperation.java:67) at org.eclipse.ui.ide.undo.AbstractWorkspaceOperation$1.run(AbstractWorkspaceOperation.java:206) at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1797) at org.eclipse.ui.ide.undo.AbstractWorkspaceOperation.execute(AbstractWorkspaceOperation.java:204) at org.eclipse.ui.actions.DeleteResourceAction$4.run(DeleteResourceAction.java:533) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) !ENTRY org.eclipse.core.resources 4 2 2007-10-31 12:30:29.375 !MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.core.resources". !STACK 0 java.lang.NullPointerException at org.jboss.ide.eclipse.as.core.modules.SingleDeployableFactory$FileDeletionListener.resourceChanged(SingleDeployableFactory.java:257) at org.eclipse.core.internal.events.NotificationManager$2.run(NotificationManager.java:282) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37) at org.eclipse.core.internal.events.NotificationManager.notify(NotificationManager.java:276) at org.eclipse.core.internal.events.NotificationManager.handleEvent(NotificationManager.java:260) at org.eclipse.core.internal.resources.Workspace.broadcastEvent(Workspace.java:305) at org.eclipse.core.internal.resources.Resource.unprotectedDelete(Resource.java:1662) at org.eclipse.core.internal.resources.Resource.delete(Resource.java:700) at org.eclipse.core.internal.resources.Project.delete(Project.java:289) at org.eclipse.ui.ide.undo.WorkspaceUndoUtil.delete(WorkspaceUndoUtil.java:578) at org.eclipse.ui.ide.undo.WorkspaceUndoUtil.delete(WorkspaceUndoUtil.java:172) at org.eclipse.ui.ide.undo.AbstractResourcesOperation.delete(AbstractResourcesOperation.java:111) at org.eclipse.ui.ide.undo.DeleteResourcesOperation.doExecute(DeleteResourcesOperation.java:67) at org.eclipse.ui.ide.undo.AbstractWorkspaceOperation$1.run(AbstractWorkspaceOperation.java:206) at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1797) at org.eclipse.ui.ide.undo.AbstractWorkspaceOperation.execute(AbstractWorkspaceOperation.java:204) at org.eclipse.ui.actions.DeleteResourceAction$4.run(DeleteResourceAction.java:533) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Denis