diff --git a/modules/social_features/social_event/modules/social_event_addtocal/src/Form/SocialAddToCalendarSettingsForm.php b/modules/social_features/social_event/modules/social_event_addtocal/src/Form/SocialAddToCalendarSettingsForm.php
index <HASH>..<HASH> 100644
--- a/modules/social_features/social_event/modules/social_event_addtocal/src/Form/SocialAddToCalendarSettingsForm.php
+++ b/modules/social_features/social_event/modules/social_event_addtocal/src/Form/SocialAddToCalendarSettingsForm.php
@@ -92,7 +92,7 @@ class SocialAddToCalendarSettingsForm extends ConfigFormBase {
           ':input[name="enable_add_to_calendar"]' => ['checked' => TRUE],
         ],
       ],
-      '#default_value' => $config->get('allowed_calendars'),
+      '#default_value' => $config->get('allowed_calendars') ?: [],
     ];
 
     return parent::buildForm($form, $form_state);
Issue #<I> by tBKoT: Fix warning when confing not exist