diff --git a/src/controller/DiagramController.php b/src/controller/DiagramController.php
--- a/src/controller/DiagramController.php
+++ b/src/controller/DiagramController.php
@@ -22,17 +22,6 @@
     $versioninfoDiagramID = $request->getURIData('versioninfodiagram');
     $versioninfoPage = $request->getURIData('versioninfopage');
 
-    if (isset($diagramphid) && !empty(trim($diagramphid))) {
-      // return PNG image data
-      $diagram = id(new DiagramVersion())->loadByDiagramPHID($diagramphid);
-      if ($diagram !== null) {
-        $response = new AphrontFileResponse();
-        $response->setMimeType('image/png');
-        $response->setContent($diagram->getData());
-        return $response;
-      }
-    }
-
     if (isset($versioninfoDiagramID) && !empty(trim($versioninfoDiagramID))) {
       // return diagram version info
       if (!isset($versioninfoPage) || empty(trim($versioninfoPage))) {