diff --git a/components/Posting/Posting.php b/components/Posting/Posting.php
index 9cfb698fca..c9e6099b86 100644
--- a/components/Posting/Posting.php
+++ b/components/Posting/Posting.php
@@ -220,25 +220,27 @@ class Posting extends Component
             }
         }
 
-        $act = Activity::create([
+        $activity = Activity::create([
             'actor_id'    => $actor->getId(),
             'verb'        => 'create',
             'object_type' => 'note',
             'object_id'   => $note->getId(),
             'source'      => 'web',
         ]);
-        DB::persist($act);
+        DB::persist($activity);
 
         DB::flush();
 
         $mentioned = [];
         foreach ($mentions as $mention) {
             foreach ($mention['mentioned'] as $m) {
-                $mentioned[] = $m->getId();
+                if (!\is_null($m)) {
+                    $mentioned[] = $m->getId();
+                }
             }
         }
 
-        Event::handle('NewNotification', [$actor, $act, ['object' => $mentioned], "{$actor->getNickname()} created note {$note->getUrl()}"]);
+        Event::handle('NewNotification', [$actor, $activity, ['object' => $mentioned], "{$actor->getNickname()} created note {$note->getUrl()}"]);
 
         return $note;
     }
diff --git a/src/Entity/Actor.php b/src/Entity/Actor.php
index ca9d1e6021..e1d16ddd2a 100644
--- a/src/Entity/Actor.php
+++ b/src/Entity/Actor.php
@@ -487,6 +487,19 @@ class Actor extends Entity
         return $url;
     }
 
+    public static function getPlaceholderUri(string $nickname, int $type = self::PERSON, int $uri_type = Router::ABSOLUTE_URL): string
+    {
+        switch ($type) {
+        case self::PERSON:
+        case self::ORGANIZATION:
+        case self::BUSINESS:
+        case self::BOT:
+            return Router::url('actor_view_nickname', ['nickname' => $nickname], $uri_type);
+        case self::GROUP:
+            return Router::url('group_actor_view_nickname', ['nickname' => $nickname], $uri_type);
+        }
+    }
+
     public function getAliases(): array
     {
         return array_keys($this->getAliasesWithIDs());
diff --git a/src/Util/Formatting.php b/src/Util/Formatting.php
index c5a00384de..7de2292e2b 100644
--- a/src/Util/Formatting.php
+++ b/src/Util/Formatting.php
@@ -35,7 +35,6 @@ namespace App\Util;
 use App\Core\Event;
 use App\Core\Log;
 use App\Entity\Actor;
-use App\Entity\Group;
 use App\Entity\Note;
 use App\Util\Exception\NicknameException;
 use App\Util\Exception\ServerException;
@@ -355,22 +354,16 @@ abstract class Formatting
             $group_matches = self::findMentionsRaw($text, '!');
             foreach ($group_matches as $group_match) {
                 $nickname = Nickname::normalize($group_match[0], check_already_used: false, check_is_allowed: false);
-                $group    = Group::getByNickname($nickname, $actor);
-
-                if (!$group instanceof Group) {
-                    continue;
-                }
-
-                $profile = $group->getActor();
+                $group    = Actor::getByNickname($nickname, Actor::GROUP);
 
                 $mentions[] = [
-                    'mentioned' => [$profile],
+                    'mentioned' => [$group],
                     'type'      => 'group',
                     'text'      => $group_match[0],
                     'position'  => $group_match[1],
                     'length'    => mb_strlen($group_match[0]),
-                    'url'       => $group->getUri(),
-                    'title'     => $group->getFullname() ?? $group->getNickname(),
+                    'url'       => !\is_null($group) ? $group->getUri() : Actor::getPlaceholderUri($nickname, Actor::GROUP),
+                    'title'     => $group?->getFullname() ?? $group?->getNickname(),
                 ];
             }