EDIT

On adding Members to a PermissionGroup I entered a '?' as wildcard character in the filter textfield of the SelectionDialog and I got an exception:

login : admin
editor version : 4.13.0.201712071146
server : localhost (localhost-dev)
schema version : 4.7.0.0.201710040000
os : Linux 4.10.0-40-generic amd64
java : 1.8.0_131
java.util.regex.PatternSyntaxException: Dangling meta character '?' near index 0
?
^
    at java.util.regex.Pattern.error(Pattern.java:1955)
    at java.util.regex.Pattern.sequence(Pattern.java:2123)
    at java.util.regex.Pattern.expr(Pattern.java:1996)
    at java.util.regex.Pattern.compile(Pattern.java:1696)
    at java.util.regex.Pattern.<init>(Pattern.java:1351)
    at java.util.regex.Pattern.compile(Pattern.java:1028)
    at java.util.regex.Pattern.matches(Pattern.java:1133)
    at java.lang.String.matches(String.java:2121)
    at eu.etaxonomy.taxeditor.ui.dialog.selection.UserSelectionDialog.callService(UserSelectionDialog.java:71)
    at eu.etaxonomy.taxeditor.ui.dialog.selection.AbstractFilteredCdmResourceSelectionDialog.search(AbstractFilteredCdmResourceSelectionDialog.java:506)
    at eu.etaxonomy.taxeditor.ui.dialog.selection.SearchDialog$2.modifyText(SearchDialog.java:161)
    at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:180)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:5227)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1340)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4561)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4151)
    at org.eclipse.jface.window.Window.runEventLoop(Window.java:818)
    at org.eclipse.jface.window.Window.open(Window.java:794)
    at eu.etaxonomy.taxeditor.ui.dialog.selection.AbstractFilteredCdmResourceSelectionDialog.getSelectionFromDialog(AbstractFilteredCdmResourceSelectionDialog.java:138)
    at eu.etaxonomy.taxeditor.ui.dialog.selection.UserSelectionDialog.select(UserSelectionDialog.java:44)
    at eu.etaxonomy.taxeditor.ui.section.group.MemberDetailSection.createNewElement(MemberDetailSection.java:55)
    at eu.etaxonomy.taxeditor.ui.section.group.MemberDetailSection.createNewElement(MemberDetailSection.java:1)
    at eu.etaxonomy.taxeditor.ui.section.AbstractEntityCollectionSection$2.run(AbstractEntityCollectionSection.java:91)
    at org.eclipse.jface.action.Action.runWithEvent(Action.java:473)
    at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:565)
    at org.eclipse.jface.action.ActionContributionItem.lambda$5(ActionContributionItem.java:436)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:5227)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1340)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4561)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4151)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$4.run(PartRenderingEngine.java:1121)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1022)
    at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:150)
    at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:693)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:610)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148)
    at eu.etaxonomy.taxeditor.Application.start(Application.java:24)
    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:673)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:610)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1519)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1492)