diff --git a/modoboa/core/api/v2/serializers.py b/modoboa/core/api/v2/serializers.py
index 1c28f2101..66a4bf1db 100644
--- a/modoboa/core/api/v2/serializers.py
+++ b/modoboa/core/api/v2/serializers.py
@@ -13,6 +13,7 @@ from modoboa.lib import fields as lib_fields
 from ... import constants
 from ... import models
 from ... import sms_backends
+from ... import app_settings
 
 
 class CoreGlobalParametersSerializer(serializers.Serializer):
@@ -106,7 +107,7 @@ class CoreGlobalParametersSerializer(serializers.Serializer):
     )
 
     # Dashboard settings
-    rss_feed_url = serializers.URLField(allow_blank=True)
+    rss_feed_url = serializers.URLField(allow_blank=True, required=False)
     hide_features_widget = serializers.BooleanField(default=False)
 
     # Notification settings
@@ -126,7 +127,7 @@ class CoreGlobalParametersSerializer(serializers.Serializer):
     log_maximum_age = serializers.IntegerField(default=365)
     items_per_page = serializers.IntegerField(default=30)
     default_top_redirection = serializers.ChoiceField(
-        default="user", choices=[""])
+        default="user", choices=app_settings.enabled_applications())
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
diff --git a/modoboa/core/sms_backends/ovh.py b/modoboa/core/sms_backends/ovh.py
index 6c9af68d5..c614ccbd2 100644
--- a/modoboa/core/sms_backends/ovh.py
+++ b/modoboa/core/sms_backends/ovh.py
@@ -75,19 +75,22 @@ class OVHBackend(SMSBackend):
         "sms_ovh_application_key": {
             "type": serializers.CharField,
             "attrs": {
-                "required": False
+                "required": False,
+                "allow_blank": True
             }
         },
         "sms_ovh_application_secret": {
             "type": serializers.CharField,
             "attrs": {
-                "required": False
+                "required": False,
+                "allow_blank": True
             }
         },
         "sms_ovh_consumer_key": {
             "type": serializers.CharField,
             "attrs": {
-                "required": False
+                "required": False,
+                "allow_blank": True
             }
         }
     }