diff --git a/lib/private/Preview/Imaginary.php b/lib/private/Preview/Imaginary.php
index 7184f7e9e76a3..830c88793beee 100644
--- a/lib/private/Preview/Imaginary.php
+++ b/lib/private/Preview/Imaginary.php
@@ -78,6 +78,9 @@ public function getCroppedThumbnail(File $file, int $maxX, int $maxY, bool $crop
 
 		// Object store
 		$stream = $file->fopen('r');
+		if (!$stream || !is_resource($stream) || feof($stream)) {
+			return null;
+		}
 
 		$httpClient = $this->service->newClient();