diff --git a/apps/federatedfilesharing/lib/AppInfo/Application.php b/apps/federatedfilesharing/lib/AppInfo/Application.php
index e89305162cd7..f59b30ab8719 100644
--- a/apps/federatedfilesharing/lib/AppInfo/Application.php
+++ b/apps/federatedfilesharing/lib/AppInfo/Application.php
@@ -21,6 +21,7 @@
 
 namespace OCA\FederatedFileSharing\AppInfo;
 
+use GuzzleHttp\Exception\ServerException;
 use OCA\FederatedFileSharing\AddressHandler;
 use OCA\FederatedFileSharing\Command\PollIncomingShares;
 use OCA\FederatedFileSharing\Controller\OcmController;
@@ -34,6 +35,7 @@
 use OCA\FederatedFileSharing\Ocm\Permissions;
 use OCA\FederatedFileSharing\TokenHandler;
 use OCP\AppFramework\App;
+use OCP\AppFramework\Http;
 use OCP\Share\Events\AcceptShare;
 use OCP\Share\Events\DeclineShare;
 
@@ -259,11 +261,19 @@ function (AcceptShare $event) use ($container) {
 			function (DeclineShare $event) use ($container) {
 				/** @var Notifications $notifications */
 				$notifications = $container->query('Notifications');
-				$notifications->sendDeclineShare(
-					$event->getRemote(),
-					$event->getRemoteId(),
-					$event->getShareToken()
-				);
+				try {
+					$notifications->sendDeclineShare(
+						$event->getRemote(),
+						$event->getRemoteId(),
+						$event->getShareToken()
+					);
+				} catch (ServerException $e) {
+					// ownCloud lower than 10.2 responded with Internal Server Error
+					// on declining non-existing share. It can't be caught outside the closure
+					if ($e->getCode() !== Http::STATUS_INTERNAL_SERVER_ERROR) {
+						throw $e;
+					}
+				}
 			}
 		);
 	}
diff --git a/apps/federatedfilesharing/tests/NotificationsTest.php b/apps/federatedfilesharing/tests/NotificationsTest.php
index 47ad6797043f..15dfa04e4173 100644
--- a/apps/federatedfilesharing/tests/NotificationsTest.php
+++ b/apps/federatedfilesharing/tests/NotificationsTest.php
@@ -34,6 +34,7 @@
 use OCP\Http\Client\IResponse;
 use OCP\IConfig;
 use OCA\FederatedFileSharing\BackgroundJob\RetryJob;
+use OCP\Share\Events\DeclineShare;
 
 class NotificationsTest extends \Test\TestCase {
 
@@ -200,4 +201,19 @@ function ($options) {
 			]
 		);
 	}
+
+	public function testDeclineEvent() {
+		$dispatcher = \OC::$server->getEventDispatcher();
+		$event = $dispatcher->dispatch(
+			DeclineShare::class,
+			new DeclineShare(
+				[
+					'remote_id' => '4354353',
+					'remote' => 'http://localhost',
+					'share_token' => 'ohno'
+				]
+			)
+		);
+		$this->assertInstanceOf(DeclineShare::class, $event);
+	}
 }