diff --git a/lib/file_wopi.php b/lib/file_wopi.php
--- a/lib/file_wopi.php
+++ b/lib/file_wopi.php
@@ -191,7 +191,7 @@
             }
         }
         catch (Exception $e) {
-            rcube::raise_error($e, true, false);
+            rcube::raise_error("WOPI disovery failed: $e->getMessage()", true, false);
 
             // Don't bail out here, it would make the kolab_files UI broken
             return array();