diff --git a/apps/dav/appinfo/info.xml b/apps/dav/appinfo/info.xml
index 0ef960b017..d9418456d8 100644
--- a/apps/dav/appinfo/info.xml
+++ b/apps/dav/appinfo/info.xml
@@ -5,7 +5,7 @@
 	<name>WebDAV</name>
 	<summary>WebDAV endpoint</summary>
 	<description>WebDAV endpoint</description>
-	<version>1.9.1</version>
+	<version>1.9.2</version>
 	<licence>agpl</licence>
 	<author>owncloud.org</author>
 	<namespace>DAV</namespace>
@@ -31,6 +31,7 @@
 			<step>OCA\DAV\Migration\CalDAVRemoveEmptyValue</step>
 			<step>OCA\DAV\Migration\BuildCalendarSearchIndex</step>
 			<step>OCA\DAV\Migration\RefreshWebcalJobRegistrar</step>
+			<step>OCA\DAV\Migration\RemoveOrphanEventsAndContacts</step>
 			<step>OCA\DAV\Migration\RemoveClassifiedEventActivity</step>
 		</post-migration>
 		<live-migration>
diff --git a/apps/dav/composer/composer/autoload_classmap.php b/apps/dav/composer/composer/autoload_classmap.php
index e9aaf35f64..d2bb79495f 100644
--- a/apps/dav/composer/composer/autoload_classmap.php
+++ b/apps/dav/composer/composer/autoload_classmap.php
@@ -158,6 +158,7 @@ return array(
     'OCA\\DAV\\Migration\\FixBirthdayCalendarComponent' => $baseDir . '/../lib/Migration/FixBirthdayCalendarComponent.php',
     'OCA\\DAV\\Migration\\RefreshWebcalJobRegistrar' => $baseDir . '/../lib/Migration/RefreshWebcalJobRegistrar.php',
     'OCA\\DAV\\Migration\\RemoveClassifiedEventActivity' => $baseDir . '/../lib/Migration/RemoveClassifiedEventActivity.php',
+    'OCA\\DAV\\Migration\\RemoveOrphanEventsAndContacts' => $baseDir . '/../lib/Migration/RemoveOrphanEventsAndContacts.php',
     'OCA\\DAV\\Migration\\Version1004Date20170825134824' => $baseDir . '/../lib/Migration/Version1004Date20170825134824.php',
     'OCA\\DAV\\Migration\\Version1004Date20170919104507' => $baseDir . '/../lib/Migration/Version1004Date20170919104507.php',
     'OCA\\DAV\\Migration\\Version1004Date20170924124212' => $baseDir . '/../lib/Migration/Version1004Date20170924124212.php',
diff --git a/apps/dav/composer/composer/autoload_static.php b/apps/dav/composer/composer/autoload_static.php
index 40fb07033f..48667db5e3 100644
--- a/apps/dav/composer/composer/autoload_static.php
+++ b/apps/dav/composer/composer/autoload_static.php
@@ -173,6 +173,7 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\Migration\\FixBirthdayCalendarComponent' => __DIR__ . '/..' . '/../lib/Migration/FixBirthdayCalendarComponent.php',
         'OCA\\DAV\\Migration\\RefreshWebcalJobRegistrar' => __DIR__ . '/..' . '/../lib/Migration/RefreshWebcalJobRegistrar.php',
         'OCA\\DAV\\Migration\\RemoveClassifiedEventActivity' => __DIR__ . '/..' . '/../lib/Migration/RemoveClassifiedEventActivity.php',
+        'OCA\\DAV\\Migration\\RemoveOrphanEventsAndContacts' => __DIR__ . '/..' . '/../lib/Migration/RemoveOrphanEventsAndContacts.php',
         'OCA\\DAV\\Migration\\Version1004Date20170825134824' => __DIR__ . '/..' . '/../lib/Migration/Version1004Date20170825134824.php',
         'OCA\\DAV\\Migration\\Version1004Date20170919104507' => __DIR__ . '/..' . '/../lib/Migration/Version1004Date20170919104507.php',
         'OCA\\DAV\\Migration\\Version1004Date20170924124212' => __DIR__ . '/..' . '/../lib/Migration/Version1004Date20170924124212.php',
diff --git a/apps/dav/lib/Migration/RemoveOrphanEventsAndContacts.php b/apps/dav/lib/Migration/RemoveOrphanEventsAndContacts.php
new file mode 100644
index 0000000000..1764358790
--- /dev/null
+++ b/apps/dav/lib/Migration/RemoveOrphanEventsAndContacts.php
@@ -0,0 +1,94 @@
+<?php
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2019 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\Migration;
+
+use OCA\DAV\CalDAV\CalDavBackend;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IDBConnection;
+use OCP\Migration\IOutput;
+use OCP\Migration\IRepairStep;
+
+class RemoveOrphanEventsAndContacts implements IRepairStep {
+
+	/** @var IDBConnection */
+	private $connection;
+
+	public function __construct(IDBConnection $connection) {
+		$this->connection = $connection;
+	}
+
+	/**
+	 * @inheritdoc
+	 */
+	public function getName(): string {
+		return 'Clean up orphan event and contact data';
+	}
+
+	/**
+	 * @inheritdoc
+	 */
+	public function run(IOutput $output) {
+		$orphanItems = $this->removeOrphanChildren('calendarobjects', 'calendars',  'calendarid');
+		$output->info(sprintf('%d events without a calendar have been cleaned up', $orphanItems));
+		$orphanItems = $this->removeOrphanChildren('calendarobjects_props', 'calendarobjects',  'objectid');
+		$output->info(sprintf('%d properties without an events have been cleaned up', $orphanItems));
+		$orphanItems = $this->removeOrphanChildren('calendarchanges', 'calendars',  'calendarid');
+		$output->info(sprintf('%d changes without a calendar have been cleaned up', $orphanItems));
+
+		$orphanItems = $this->removeOrphanChildren('cards', 'addressbooks',  'addressbookid');
+		$output->info(sprintf('%d contacts without an addressbook have been cleaned up', $orphanItems));
+		$orphanItems = $this->removeOrphanChildren('cards_properties', 'cards',  'cardid');
+		$output->info(sprintf('%d properties without a contact have been cleaned up', $orphanItems));
+		$orphanItems = $this->removeOrphanChildren('addressbookchanges', 'addressbooks',  'addressbookid');
+		$output->info(sprintf('%d changes without an addressbook have been cleaned up', $orphanItems));
+	}
+
+	protected function removeOrphanChildren($childTable, $parentTable, $parentId): int {
+		$qb = $this->connection->getQueryBuilder();
+
+		$qb->select('c.id')
+			->from($childTable, 'c')
+			->leftJoin('c', $parentTable, 'p', $qb->expr()->eq('c.' . $parentId, 'p.id'))
+			->where($qb->expr()->isNull('p.id'));
+		$result = $qb->execute();
+
+		$orphanItems = array();
+		while ($row = $result->fetch()) {
+			$orphanItems[] = (int) $row['id'];
+		}
+		$result->closeCursor();
+
+		if (!empty($orphanItems)) {
+			$qb->delete($childTable)
+				->where($qb->expr()->in('id', $qb->createParameter('ids')));
+
+			$orphanItemsBatch = array_chunk($orphanItems, 200);
+			foreach ($orphanItemsBatch as $items) {
+				$qb->setParameter('ids', $items, IQueryBuilder::PARAM_INT_ARRAY);
+				$qb->execute();
+			}
+		}
+
+		return count($orphanItems);
+	}
+}