diff --git a/apps/federatedfilesharing/lib/FederatedShareProvider.php b/apps/federatedfilesharing/lib/FederatedShareProvider.php
index 4d60744fe3..13348a1d7b 100644
--- a/apps/federatedfilesharing/lib/FederatedShareProvider.php
+++ b/apps/federatedfilesharing/lib/FederatedShareProvider.php
@@ -493,7 +493,7 @@ class FederatedShareProvider implements IShareProvider {
 			throw new ShareNotFound();
 		}
 
-		return (int)$data['remote_id'];
+		return (string)$data['remote_id'];
 	}
 
 	/**
diff --git a/apps/federatedfilesharing/lib/Migration/Version1010Date20200630191755.php b/apps/federatedfilesharing/lib/Migration/Version1010Date20200630191755.php
index 7376c8d9e7..afd41c20f6 100644
--- a/apps/federatedfilesharing/lib/Migration/Version1010Date20200630191755.php
+++ b/apps/federatedfilesharing/lib/Migration/Version1010Date20200630191755.php
@@ -48,8 +48,9 @@ class Version1010Date20200630191755 extends SimpleMigrationStep {
 				'notnull' => true,
 			]);
 			$table->addColumn('remote_id', Types::STRING, [
-				'notnull' => true,
+				'notnull' => false,
 				'length' => 255,
+				'default' => '',
 			]);
 			$table->setPrimaryKey(['share_id'], 'federated_res_pk');
 //			$table->addUniqueIndex(['share_id'], 'share_id_index');
diff --git a/apps/federatedfilesharing/lib/Migration/Version1011Date20201120125158.php b/apps/federatedfilesharing/lib/Migration/Version1011Date20201120125158.php
index 1f32f2cced..e89838c06f 100644
--- a/apps/federatedfilesharing/lib/Migration/Version1011Date20201120125158.php
+++ b/apps/federatedfilesharing/lib/Migration/Version1011Date20201120125158.php
@@ -29,10 +29,19 @@ use Closure;
 use Doctrine\DBAL\Types\Type;
 use Doctrine\DBAL\Types\Types;
 use OCP\DB\ISchemaWrapper;
+use OCP\IDBConnection;
 use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
 
 class Version1011Date20201120125158 extends SimpleMigrationStep {
+
+	/** @var IDBConnection */
+	private $connection;
+
+	public function __construct(IDBConnection $connection) {
+		$this->connection = $connection;
+	}
+
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options) {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();
@@ -41,6 +50,7 @@ class Version1011Date20201120125158 extends SimpleMigrationStep {
 			$table = $schema->getTable('federated_reshares');
 			$remoteIdColumn = $table->getColumn('remote_id');
 			if ($remoteIdColumn && $remoteIdColumn->getType()->getName() !== Types::STRING) {
+				$remoteIdColumn->setNotnull(false);
 				$remoteIdColumn->setType(Type::getType(Types::STRING));
 				$remoteIdColumn->setOptions(['length' => 255]);
 				$remoteIdColumn->setDefault('');
@@ -50,4 +60,12 @@ class Version1011Date20201120125158 extends SimpleMigrationStep {
 
 		return null;
 	}
+
+	public function postSchemaChange(IOutput $output, \Closure $schemaClosure, array $options) {
+		$qb = $this->connection->getQueryBuilder();
+		$qb->update('federated_reshares')
+			->set('remote_id', $qb->createNamedParameter(''))
+			->where($qb->expr()->eq('remote_id', $qb->createNamedParameter('-1')));
+		$qb->execute();
+	}
 }
diff --git a/apps/federatedfilesharing/lib/Notifications.php b/apps/federatedfilesharing/lib/Notifications.php
index 5df3c4af89..b0add6befb 100644
--- a/apps/federatedfilesharing/lib/Notifications.php
+++ b/apps/federatedfilesharing/lib/Notifications.php
@@ -133,12 +133,12 @@ class Notifications {
 	 *
 	 * @param string $token
 	 * @param string $id remote Id
-	 * @param int $shareId internal share Id
+	 * @param string $shareId internal share Id
 	 * @param string $remote remote address of the owner
 	 * @param string $shareWith
 	 * @param int $permission
 	 * @param string $filename
-	 * @return array
+	 * @return array|false
 	 * @throws \OC\HintException
 	 * @throws \OC\ServerNotAvailableException
 	 */
@@ -182,7 +182,7 @@ class Notifications {
 	 * send server-to-server unshare to remote server
 	 *
 	 * @param string $remote url
-	 * @param int $id share id
+	 * @param string $id share id
 	 * @param string $token
 	 * @return bool
 	 */
@@ -194,7 +194,7 @@ class Notifications {
 	 * send server-to-server unshare to remote server
 	 *
 	 * @param string $remote url
-	 * @param int $id share id
+	 * @param string $id share id
 	 * @param string $token
 	 * @return bool
 	 */
diff --git a/apps/files_sharing/lib/Migration/Version11300Date20201120141438.php b/apps/files_sharing/lib/Migration/Version11300Date20201120141438.php
index 6183324982..dfc5bc68a0 100644
--- a/apps/files_sharing/lib/Migration/Version11300Date20201120141438.php
+++ b/apps/files_sharing/lib/Migration/Version11300Date20201120141438.php
@@ -2,16 +2,48 @@
 
 declare(strict_types=1);
 
+/*
+ * @copyright Copyright (c) 2020 Julius Härtl <jus@bitgrid.net>
+ *
+ * @author Julius Härtl <jus@bitgrid.net>
+ *
+ * @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\Files_Sharing\Migration;
 
 use Closure;
 use Doctrine\DBAL\Types\Type;
 use Doctrine\DBAL\Types\Types;
 use OCP\DB\ISchemaWrapper;
+use OCP\IDBConnection;
 use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
 
 class Version11300Date20201120141438 extends SimpleMigrationStep {
+
+	/** @var IDBConnection */
+	private $connection;
+
+	public function __construct(IDBConnection $connection) {
+		$this->connection = $connection;
+	}
+
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();
@@ -35,9 +67,9 @@ class Version11300Date20201120141438 extends SimpleMigrationStep {
 				'length' => 512,
 			]);
 			$table->addColumn('remote_id', Types::STRING, [
-				'notnull' => true,
+				'notnull' => false,
 				'length' => 255,
-				'default' => -1,
+				'default' => '',
 			]);
 			$table->addColumn('share_token', Types::STRING, [
 				'notnull' => true,
@@ -79,11 +111,21 @@ class Version11300Date20201120141438 extends SimpleMigrationStep {
 			$table = $schema->getTable('share_external');
 			$remoteIdColumn = $table->getColumn('remote_id');
 			if ($remoteIdColumn && $remoteIdColumn->getType()->getName() !== Types::STRING) {
+				$remoteIdColumn->setNotnull(false);
 				$remoteIdColumn->setType(Type::getType(Types::STRING));
 				$remoteIdColumn->setOptions(['length' => 255]);
+				$remoteIdColumn->setDefault('');
 			}
 		}
 
 		return $schema;
 	}
+
+	public function postSchemaChange(IOutput $output, \Closure $schemaClosure, array $options) {
+		$qb = $this->connection->getQueryBuilder();
+		$qb->update('share_external')
+			->set('remote_id', $qb->createNamedParameter(''))
+			->where($qb->expr()->eq('remote_id', $qb->createNamedParameter('-1')));
+		$qb->execute();
+	}
 }
diff --git a/apps/files_sharing/tests/External/ManagerTest.php b/apps/files_sharing/tests/External/ManagerTest.php
index 22005c8fc6..2734e3cce6 100644
--- a/apps/files_sharing/tests/External/ManagerTest.php
+++ b/apps/files_sharing/tests/External/ManagerTest.php
@@ -149,6 +149,7 @@ class ManagerTest extends TestCase {
 			'shareType' => IShare::TYPE_USER,
 			'accepted' => false,
 			'user' => $this->uid,
+			'remote_id' => '2342'
 		];
 		$shareData2 = $shareData1;
 		$shareData2['token'] = 'token2';
@@ -158,8 +159,8 @@ class ManagerTest extends TestCase {
 		$this->userManager->expects($this->any())->method('get')->willReturn($this->user);
 		$this->groupManager->expects($this->any())->method(('getUserGroups'))->willReturn([]);
 
-		$this->manager->expects($this->at(0))->method('tryOCMEndPoint')->with('http://localhost', 'token1', -1, 'accept')->willReturn(false);
-		$this->manager->expects($this->at(1))->method('tryOCMEndPoint')->with('http://localhost', 'token3', -1, 'decline')->willReturn(false);
+		$this->manager->expects($this->at(0))->method('tryOCMEndPoint')->with('http://localhost', 'token1', '2342', 'accept')->willReturn(false);
+		$this->manager->expects($this->at(1))->method('tryOCMEndPoint')->with('http://localhost', 'token3', '2342', 'decline')->willReturn(false);
 
 		// Add a share for "user"
 		$this->assertSame(null, call_user_func_array([$this->manager, 'addShare'], $shareData1));