diff --git a/apps/dav/lib/CalDAV/Activity/Backend.php b/apps/dav/lib/CalDAV/Activity/Backend.php
index 6cf09f6de4..6a557fef7b 100644
--- a/apps/dav/lib/CalDAV/Activity/Backend.php
+++ b/apps/dav/lib/CalDAV/Activity/Backend.php
@@ -112,7 +112,7 @@ class Backend {
 
 		$event = $this->activityManager->generateEvent();
 		$event->setApp('dav')
-			->setObject(Extension::CALENDAR, $calendarData['id'])
+			->setObject(Extension::CALENDAR, (int) $calendarData['id'])
 			->setType(Extension::CALENDAR)
 			->setAuthor($currentUser);
 
@@ -162,7 +162,7 @@ class Backend {
 
 		$event = $this->activityManager->generateEvent();
 		$event->setApp('dav')
-			->setObject(Extension::CALENDAR, $calendarData['id'])
+			->setObject(Extension::CALENDAR, (int) $calendarData['id'])
 			->setType(Extension::CALENDAR)
 			->setAuthor($currentUser);
 
@@ -387,7 +387,7 @@ class Backend {
 
 		$event = $this->activityManager->generateEvent();
 		$event->setApp('dav')
-			->setObject(Extension::CALENDAR, $calendarData['id'])
+			->setObject(Extension::CALENDAR, (int) $calendarData['id'])
 			->setType($object['type'] === 'event' ? Extension::CALENDAR_EVENT : Extension::CALENDAR_TODO)
 			->setAuthor($currentUser);
 
diff --git a/lib/private/Activity/Event.php b/lib/private/Activity/Event.php
index c53335a316..16c65c2085 100644
--- a/lib/private/Activity/Event.php
+++ b/lib/private/Activity/Event.php
@@ -539,10 +539,13 @@ class Event implements IEvent {
 			$this->getAffectedUser() !== ''
 			&&
 			$this->getTimestamp() !== 0
+			/**
+			 * Disabled for BC with old activities
 			&&
 			$this->getObjectType() !== ''
 			&&
-			$this->getObjectId() !== ''
+			$this->getObjectId() !== 0
+			 */
 		;
 	}
 }
diff --git a/lib/private/Activity/Manager.php b/lib/private/Activity/Manager.php
index 35668a267e..9c1629d79c 100644
--- a/lib/private/Activity/Manager.php
+++ b/lib/private/Activity/Manager.php
@@ -173,14 +173,6 @@ class Manager implements IManager {
 	 * @throws \BadMethodCallException if required values have not been set
 	 */
 	public function publish(IEvent $event) {
-		$this->publishToConsumers($event, false);
-	}
-
-	/**
-	 * @param IEvent $event
-	 * @param bool $legacyActivity
-	 */
-	protected function publishToConsumers(IEvent $event, $legacyActivity) {
 		if ($event->getAuthor() === '') {
 			if ($this->session->getUser() instanceof IUser) {
 				$event->setAuthor($this->session->getUser()->getUID());
@@ -191,7 +183,7 @@ class Manager implements IManager {
 			$event->setTimestamp(time());
 		}
 
-		if (!$legacyActivity && !$event->isValid()) {
+		if (!$event->isValid()) {
 			throw new \BadMethodCallException('The given event is invalid');
 		}
 
@@ -222,7 +214,7 @@ class Manager implements IManager {
 			->setObject('', 0, $file)
 			->setLink($link);
 
-		$this->publishToConsumers($event, true);
+		$this->publish($event);
 	}
 
 	/**