diff --git a/protected/humhub/modules/user/models/forms/EditGroupForm.php b/protected/humhub/modules/user/models/forms/EditGroupForm.php
index 8189a4f14c..4654b32b38 100644
--- a/protected/humhub/modules/user/models/forms/EditGroupForm.php
+++ b/protected/humhub/modules/user/models/forms/EditGroupForm.php
@@ -52,10 +52,12 @@ class EditGroupForm extends Group
 
         $existingSpaceIds = GroupSpace::find()->where(['group_id' => $this->id])->select('space_id')->column();
         $newSpaceIds = [];
-        foreach ($this->defaultSpaceGuid as $spaceGuid) {
-            $space = Space::findOne(['guid' => $spaceGuid]);
-            if ($space !== null) {
-                $newSpaceIds[] = $space->id;
+        if (is_array($this->defaultSpaceGuid)) {
+            foreach ($this->defaultSpaceGuid as $spaceGuid) {
+                $space = Space::findOne(['guid' => $spaceGuid]);
+                if ($space !== null) {
+                    $newSpaceIds[] = $space->id;
+                }
             }
         }