Index: src/wp-admin/nav-menus.php
===================================================================
--- src/wp-admin/nav-menus.php	(revision 60261)
+++ src/wp-admin/nav-menus.php	(working copy)
@@ -1212,7 +1212,7 @@
 											<div class="menu-settings-input checkbox-input">
 												<input type="checkbox"<?php checked( $checked ); ?> name="menu-locations[<?php echo esc_attr( $location ); ?>]" id="locations-<?php echo esc_attr( $location ); ?>" value="<?php echo esc_attr( $nav_menu_selected_id ); ?>" />
 												<label for="locations-<?php echo esc_attr( $location ); ?>"><?php echo $description; ?></label>
-												<?php if ( ! empty( $menu_locations[ $location ] ) && $menu_locations[ $location ] !== $nav_menu_selected_id ) : ?>
+												<?php if ( ! empty( $menu_locations[ $location ] ) && is_nav_menu( $menu_locations[ $location ] ) && $menu_locations[ $location ] !== $nav_menu_selected_id ) : ?>
 													<span class="theme-location-set">
 													<?php
 														printf(