Index: branches/release-35/lib/MT/App.pm
===================================================================
--- branches/release-35/lib/MT/App.pm (revision 1873)
+++ branches/release-35/lib/MT/App.pm (revision 1969)
@@ -2059,5 +2059,9 @@
     }
     $tmpl->param( $param );
-    $app->l10n_filter($tmpl->output);
+    my $out = $tmpl->output;
+    if (!defined $out) {
+        return $tmpl->errstr;
+    }
+    return $app->l10n_filter($out);
 }