diff --git a/apps/encryption/lib/crypto/encryption.php b/apps/encryption/lib/crypto/encryption.php
index 907a6437f5b3..6eff66e72bea 100644
--- a/apps/encryption/lib/crypto/encryption.php
+++ b/apps/encryption/lib/crypto/encryption.php
@@ -547,4 +547,17 @@ protected function stripPartFileExtension($path) {
 		return $path;
 	}
 
+	/**
+	 * Check if the module is ready to be used by that specific user.
+	 * In case a module is not ready - because e.g. key pairs have not been generated
+	 * upon login this method can return false before any operation starts and might
+	 * cause issues during operations.
+	 *
+	 * @param string $user
+	 * @return boolean
+	 * @since 9.1.0
+	 */
+	public function isReadyForUser($user) {
+		return $this->keyManager->userHasKeys($user);
+	}
 }
diff --git a/apps/encryption/lib/keymanager.php b/apps/encryption/lib/keymanager.php
index 12fa5f92bd5e..0accfb7900ac 100644
--- a/apps/encryption/lib/keymanager.php
+++ b/apps/encryption/lib/keymanager.php
@@ -493,6 +493,7 @@ public function getShareKey($path, $uid) {
 	 */
 	public function userHasKeys($userId) {
 		$privateKey = $publicKey = true;
+		$exception = null;
 
 		try {
 			$this->getPrivateKey($userId);
diff --git a/apps/files/command/transferownership.php b/apps/files/command/transferownership.php
index 6bf2fae6bdfc..1f46efdde0d8 100644
--- a/apps/files/command/transferownership.php
+++ b/apps/files/command/transferownership.php
@@ -97,6 +97,12 @@ protected function execute(InputInterface $input, OutputInterface $output) {
 			$output->writeln("<error>Unknown destination user $this->destinationUser</error>");
 			return;
 		}
+		
+		// target user has to be ready
+		if (!\OC::$server->getEncryptionManager()->isReadyForUser($this->destinationUser)) {
+			$output->writeln("<error>The target user is not ready to accept files. The user has at least to be logged in once.</error>");
+			return;
+		}
 
 		$date = date('c');
 		$this->finalTarget = "$this->destinationUser/files/transferred from $this->sourceUser on $date";
diff --git a/lib/private/encryption/manager.php b/lib/private/encryption/manager.php
index d45bbf07ee96..8714d1618074 100644
--- a/lib/private/encryption/manager.php
+++ b/lib/private/encryption/manager.php
@@ -117,6 +117,25 @@ public function isReady() {
 	}
 
 	/**
+	 * @param string $user
+	 */
+	public function isReadyForUser($user) {
+		if (!$this->isReady()) {
+			return false;
+		}
+
+		foreach ($this->getEncryptionModules() as $module) {
+			/** @var IEncryptionModule $m */
+			$m = call_user_func($module['callback']);
+			if (!$m->isReadyForUser($user)) {
+				return false;
+			}
+		}
+
+		return true;
+	}
+
+		/**
 	 * Registers an callback function which must return an encryption module instance
 	 *
 	 * @param string $id
diff --git a/lib/public/encryption/iencryptionmodule.php b/lib/public/encryption/iencryptionmodule.php
index df30dd57cee7..8d20a1ab57d1 100644
--- a/lib/public/encryption/iencryptionmodule.php
+++ b/lib/public/encryption/iencryptionmodule.php
@@ -168,4 +168,16 @@ public function encryptAll(InputInterface $input, OutputInterface $output);
 	 */
 	public function prepareDecryptAll(InputInterface $input, OutputInterface $output, $user = '');
 
+	/**
+	 * Check if the module is ready to be used by that specific user.
+	 * In case a module is not ready - because e.g. key pairs have not been generated
+	 * upon login this method can return false before any operation starts and might
+	 * cause issues during operations.
+	 *
+	 * @param string $user
+	 * @return boolean
+	 * @since 9.1.0
+	 */
+	public function isReadyForUser($user);
+
 }
diff --git a/tests/lib/files/storage/wrapper/encryption.php b/tests/lib/files/storage/wrapper/encryption.php
index 651299a3eaba..21f7d9f09b92 100644
--- a/tests/lib/files/storage/wrapper/encryption.php
+++ b/tests/lib/files/storage/wrapper/encryption.php
@@ -5,6 +5,7 @@
 use OC\Encryption\Util;
 use OC\Files\Storage\Temporary;
 use OC\Files\View;
+use OC\User\Manager;
 use Test\Files\Storage\Storage;
 
 class Encryption extends Storage {
@@ -118,7 +119,7 @@ protected function setUp() {
 		$this->util = $this->getMock(
 			'\OC\Encryption\Util',
 			['getUidAndFilename', 'isFile', 'isExcluded'],
-			[new View(), new \OC\User\Manager(), $this->groupManager, $this->config, $this->arrayCache]);
+			[new View(), new Manager(), $this->groupManager, $this->config, $this->arrayCache]);
 		$this->util->expects($this->any())
 			->method('getUidAndFilename')
 			->willReturnCallback(function ($path) {
@@ -200,7 +201,7 @@ protected function setUp() {
 	protected function buildMockModule() {
 		$this->encryptionModule = $this->getMockBuilder('\OCP\Encryption\IEncryptionModule')
 			->disableOriginalConstructor()
-			->setMethods(['getId', 'getDisplayName', 'begin', 'end', 'encrypt', 'decrypt', 'update', 'shouldEncrypt', 'getUnencryptedBlockSize', 'isReadable', 'encryptAll', 'prepareDecryptAll'])
+			->setMethods(['getId', 'getDisplayName', 'begin', 'end', 'encrypt', 'decrypt', 'update', 'shouldEncrypt', 'getUnencryptedBlockSize', 'isReadable', 'encryptAll', 'prepareDecryptAll', 'isReadyForUser'])
 			->getMock();
 
 		$this->encryptionModule->expects($this->any())->method('getId')->willReturn('UNIT_TEST_MODULE');
@@ -543,7 +544,7 @@ public function testGetHeader($path, $strippedPathExists, $strippedPath) {
 			->setConstructorArgs(
 				[
 					new View(),
-					new \OC\User\Manager(),
+					new Manager(),
 					$this->groupManager,
 					$this->config,
 					$this->arrayCache
@@ -608,7 +609,7 @@ public function testGetHeaderAddLegacyModule($header, $isEncrypted, $expected) {
 			->disableOriginalConstructor()->getMock();
 
 		$util = $this->getMockBuilder('\OC\Encryption\Util')
-			->setConstructorArgs([new View(), new \OC\User\Manager(), $this->groupManager, $this->config, $this->arrayCache])
+			->setConstructorArgs([new View(), new Manager(), $this->groupManager, $this->config, $this->arrayCache])
 			->getMock();
 
 		$cache = $this->getMockBuilder('\OC\Files\Cache\Cache')
diff --git a/tests/lib/files/stream/encryption.php b/tests/lib/files/stream/encryption.php
index afb31f2822d0..20a4100d2ff2 100644
--- a/tests/lib/files/stream/encryption.php
+++ b/tests/lib/files/stream/encryption.php
@@ -311,7 +311,7 @@ public function testWriteToNonSeekableStorage($testFile) {
 	protected function buildMockModule() {
 		$encryptionModule = $this->getMockBuilder('\OCP\Encryption\IEncryptionModule')
 			->disableOriginalConstructor()
-			->setMethods(['getId', 'getDisplayName', 'begin', 'end', 'encrypt', 'decrypt', 'update', 'shouldEncrypt', 'getUnencryptedBlockSize', 'isReadable', 'encryptAll', 'prepareDecryptAll'])
+			->setMethods(['getId', 'getDisplayName', 'begin', 'end', 'encrypt', 'decrypt', 'update', 'shouldEncrypt', 'getUnencryptedBlockSize', 'isReadable', 'encryptAll', 'prepareDecryptAll', 'isReadyForUser'])
 			->getMock();
 
 		$encryptionModule->expects($this->any())->method('getId')->willReturn('UNIT_TEST_MODULE');