diff --git a/apps/files_external/lib/Command/Notify.php b/apps/files_external/lib/Command/Notify.php
index 60639f7dbe478..5013d88539b3c 100644
--- a/apps/files_external/lib/Command/Notify.php
+++ b/apps/files_external/lib/Command/Notify.php
@@ -326,7 +326,10 @@ private function reconnectToDatabase(IDBConnection $connection, OutputInterface
 
 	private function selfTest(IStorage $storage, INotifyHandler $notifyHandler, OutputInterface $output) {
 		usleep(100 * 1000); //give time for the notify to start
-		$storage->file_put_contents('/.nc_test_file.txt', 'test content');
+		if (!$storage->file_put_contents('/.nc_test_file.txt', 'test content')) {
+			$output->writeln("Failed to create test file for self-test");
+			return;
+		}
 		$storage->mkdir('/.nc_test_folder');
 		$storage->file_put_contents('/.nc_test_folder/subfile.txt', 'test content');
 
diff --git a/lib/private/Files/Storage/Common.php b/lib/private/Files/Storage/Common.php
index 3473eebc4a0e1..23f63dee2641e 100644
--- a/lib/private/Files/Storage/Common.php
+++ b/lib/private/Files/Storage/Common.php
@@ -207,6 +207,9 @@ public function file_get_contents($path) {
 
 	public function file_put_contents($path, $data) {
 		$handle = $this->fopen($path, "w");
+		if (!$handle) {
+			return false;
+		}
 		$this->removeCachedFile($path);
 		$count = fwrite($handle, $data);
 		fclose($handle);