copy the listed files from harmattan theme v4.*... (files location is) [usr/share/themes/harmattan-theme/images] wmTaskSwitcherIconPressed.png wmTaskSwitcherIconHighlight.png wmTaskSwitcherIcon.png wmTaskLauncherIconPressed.png wmTaskLauncherIcon.png wmSeparator.png ApplicationShortcutApplet.png ApplicationShortcutAppletPressed.png and replace them back after upgrading to harmattan-theme v5.1 and then reboot... hope it solves your problem...