diff --git a/src/applications/files/document/PhabricatorDocumentEngine.php b/src/applications/files/document/PhabricatorDocumentEngine.php
--- a/src/applications/files/document/PhabricatorDocumentEngine.php
+++ b/src/applications/files/document/PhabricatorDocumentEngine.php
@@ -28,7 +28,11 @@
   }
 
   final public function canRenderDocument(PhabricatorDocumentRef $ref) {
-    return $this->canRenderDocumentType($ref);
+    try {
+      return $this->canRenderDocumentType($ref);
+    } catch (Throwable $e) {
+      return false;
+    }
   }
 
   public function canDiffDocuments(