Error when opening archives view

When I open archives view on (a new workspace?) the error log goes to front and shows 3 of these:

org.eclipse.core.runtime.CoreException: The default variable is not countable. Failed expression:
org.eclipse.core.internal.expressions.CountExpression@fc8b685d

at org.eclipse.core.internal.expressions.Expressions.getAsICountable(Expressions.java:173)

at org.eclipse.core.internal.expressions.CountExpression.evaluate(CountExpression.java:85)

at org.eclipse.core.internal.expressions.CompositeExpression.evaluateOr(CompositeExpression.java:68)

at org.eclipse.core.internal.expressions.OrExpression.evaluate(OrExpression.java:21)

at org.eclipse.core.internal.expressions.CompositeExpression.evaluateAnd(CompositeExpression.java:53)

at org.eclipse.core.internal.expressions.EnablementExpression.evaluate(EnablementExpression.java:53)

at org.eclipse.ui.internal.navigator.actions.CommonActionProviderDescriptor.isEnabledFor(CommonActionProviderDescriptor.java:241)

at org.eclipse.ui.internal.navigator.actions.CommonActionDescriptorManager.addProviderIfRelevant(CommonActionDescriptorManager.java:211)

at org.eclipse.ui.internal.navigator.actions.CommonActionDescriptorManager.findRelevantActionDescriptors(CommonActionDescriptorManager.java:188)

at org.eclipse.ui.navigator.NavigatorActionService.fillActionBars(NavigatorActionService.java:231)

at org.eclipse.ui.internal.navigator.CommonNavigatorManager.selectionChanged(CommonNavigatorManager.java:220)

at org.eclipse.jface.viewers.Viewer$2.run(Viewer.java:162)

at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37)

at org.eclipse.core.runtime.Platform.run(Platform.java:880)

at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:48)

at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)

at org.eclipse.jface.viewers.Viewer.fireSelectionChanged(Viewer.java:160)

at org.eclipse.jface.viewers.StructuredViewer.updateSelection(StructuredViewer.java:2062)

at org.eclipse.jface.viewers.StructuredViewer.handleSelect(StructuredViewer.java:1138)

at org.eclipse.ui.navigator.CommonViewer.handleSelect(CommonViewer.java:388)

at org.eclipse.jface.viewers.StructuredViewer$4.widgetSelected(StructuredViewer.java:1168)

at org.eclipse.jface.util.OpenStrategy.fireSelectionEvent(OpenStrategy.java:227)

at org.eclipse.jface.util.OpenStrategy.access$3(OpenStrategy.java:221)

at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:388)

at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)

at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003)

at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3823)

at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3422)

at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2382)

at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2346)

at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2198)

at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:493)

at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:288)

at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:488)

at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)

at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)

at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:193)

at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)

at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)

at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:382)

at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)

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 org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:549)

at org.eclipse.equinox.launcher.Main.basicRun(Main.java:504)

at org.eclipse.equinox.launcher.Main.run(Main.java:1236)