diff -r 5f1e1cc17e8a -r 3c36874da933 server/src/app/Http/Controllers/Api/DocumentController.php
--- a/server/src/app/Http/Controllers/Api/DocumentController.php	Mon May 30 00:32:20 2016 +0200
+++ b/server/src/app/Http/Controllers/Api/DocumentController.php	Mon May 30 11:27:18 2016 +0200
@@ -89,7 +89,7 @@
         $transcriptDef = $doc->getTranscript();
 
         $transcriptUrl = $transcriptDef['url'];
-        if(empty($transcriptUrl)) {
+        if(empty($transcriptUrl) || empty($transcriptDef['conforms-to'])) {
             abort(404);
         }
         $converter = $this->transcriptManager->getConverterUrl($transcriptDef['conforms-to'], $doc, $transcriptUrl);