diff --git a/lib/federation/activity_pub/utils.ex b/lib/federation/activity_pub/utils.ex
index 0b9a96b6..eeb802a8 100644
--- a/lib/federation/activity_pub/utils.ex
+++ b/lib/federation/activity_pub/utils.ex
@@ -126,6 +126,10 @@ defmodule Mobilizon.Federation.ActivityPub.Utils do
             "@type" => "sc:Boolean",
             "@id" => "mz:isOnline"
           },
+          "externalParticipationUrl" => %{
+            "@id" => "mz:externalParticipationUrl",
+            "@type" => "sc:URL"
+          },
           "PropertyValue" => "sc:PropertyValue",
           "value" => "sc:value",
           "propertyID" => "sc:propertyID",
diff --git a/lib/graphql/schema/custom/timezone.ex b/lib/graphql/schema/custom/timezone.ex
index cd20efc0..ad409acf 100644
--- a/lib/graphql/schema/custom/timezone.ex
+++ b/lib/graphql/schema/custom/timezone.ex
@@ -17,6 +17,8 @@ defmodule Mobilizon.GraphQL.Schema.Custom.Timezone do
 
   @spec decode(Absinthe.Blueprint.Input.String.t()) :: {:ok, term} | :error
   @spec decode(Absinthe.Blueprint.Input.Null.t()) :: {:ok, nil}
+  defp decode(%Absinthe.Blueprint.Input.String{value: ""}), do: {:ok, nil}
+
   defp decode(%Absinthe.Blueprint.Input.String{value: value}) do
     if Tzdata.zone_exists?(value),
       do: {:ok, value},
diff --git a/src/views/Group/CreateView.vue b/src/views/Group/CreateView.vue
index 232b4975..94fa1a3e 100644
--- a/src/views/Group/CreateView.vue
+++ b/src/views/Group/CreateView.vue
@@ -287,12 +287,16 @@ const buildVariables = computed(() => {
     preferredUsername: group.value.preferredUsername,
     name: group.value.name,
     summary: group.value.summary,
-    physicalAddress: cloneGroup.physicalAddress,
     visibility: group.value.visibility,
     openness: group.value.openness,
     manuallyApprovesFollowers: group.value.manuallyApprovesFollowers,
   };
 
+  if (cloneGroup.physicalAddress?.id || cloneGroup.physicalAddress?.geom) {
+    // @ts-expect-error No type for this variable
+    groupBasic.physicalAddress = cloneGroup.physicalAddress;
+  }
+
   if (avatarFile.value) {
     avatarObj = {
       avatar: {
diff --git a/src/views/Group/GroupSettings.vue b/src/views/Group/GroupSettings.vue
index f49ba39d..d32d32cb 100644
--- a/src/views/Group/GroupSettings.vue
+++ b/src/views/Group/GroupSettings.vue
@@ -345,7 +345,7 @@ const currentAddress = computed({
     return editableGroup.value?.physicalAddress ?? null;
   },
   set(address: IAddress | null) {
-    if (editableGroup.value && address) {
+    if (editableGroup.value && address && (address.id || address.geom)) {
       editableGroup.value = {
         ...editableGroup.value,
         physicalAddress: address,