diff -up evolution-3.28.5/src/calendar/gui/e-comp-editor.c.crash-empty-attendee evolution-3.28.5/src/calendar/gui/e-comp-editor.c
--- evolution-3.28.5/src/calendar/gui/e-comp-editor.c.crash-empty-attendee	2018-07-30 15:37:05.000000000 +0200
+++ evolution-3.28.5/src/calendar/gui/e-comp-editor.c	2019-06-28 11:36:27.645365528 +0200
@@ -2610,6 +2610,7 @@ e_comp_editor_fill_component (ECompEdito
 			      icalcomponent *component)
 {
 	ECompEditorClass *comp_editor_class;
+	GtkWidget *focused_widget;
 	gboolean is_valid;
 
 	g_return_val_if_fail (E_IS_COMP_EDITOR (comp_editor), FALSE);
@@ -2619,8 +2620,30 @@ e_comp_editor_fill_component (ECompEdito
 	g_return_val_if_fail (comp_editor_class != NULL, FALSE);
 	g_return_val_if_fail (comp_editor_class->fill_component != NULL, FALSE);
 
+	focused_widget = gtk_window_get_focus (GTK_WINDOW (comp_editor));
+	if (focused_widget) {
+		GtkWidget *parent, *ce_widget = GTK_WIDGET (comp_editor);
+
+		/* When a cell-renderer is focused and editing the cell content,
+		   then unfocus it may mean to free the currently focused widget,
+		   thus get the GtkTreeView in such cases. */
+		parent = focused_widget;
+		while (parent = gtk_widget_get_parent (parent), parent && parent != ce_widget) {
+			if (GTK_IS_TREE_VIEW (parent)) {
+				focused_widget = parent;
+				break;
+			}
+		}
+
+		/* Save any pending changes */
+		gtk_window_set_focus (GTK_WINDOW (comp_editor), NULL);
+	}
+
 	is_valid = comp_editor_class->fill_component (comp_editor, component);
 
+	if (focused_widget)
+		gtk_window_set_focus (GTK_WINDOW (comp_editor), focused_widget);
+
 	if (is_valid && comp_editor->priv->validation_alert) {
 		e_alert_response (comp_editor->priv->validation_alert, GTK_RESPONSE_CLOSE);
 		g_clear_object (&comp_editor->priv->validation_alert);
diff -up evolution-3.28.5/src/modules/calendar/e-cal-shell-content.c.crash-empty-attendee evolution-3.28.5/src/modules/calendar/e-cal-shell-content.c
--- evolution-3.28.5/src/modules/calendar/e-cal-shell-content.c.crash-empty-attendee	2018-07-30 15:37:05.000000000 +0200
+++ evolution-3.28.5/src/modules/calendar/e-cal-shell-content.c	2019-06-28 11:36:27.645365528 +0200
@@ -847,9 +847,9 @@ cal_shell_content_get_attendee_prop (ica
 	while (prop != NULL) {
 		const gchar *attendee;
 
-		attendee = icalproperty_get_attendee (prop);
+		attendee = itip_strip_mailto (icalproperty_get_attendee (prop));
 
-		if (g_str_equal (itip_strip_mailto (attendee), address))
+		if (attendee && g_ascii_strcasecmp (attendee, address) == 0)
 			return prop;
 
 		prop = icalcomponent_get_next_property (