diff --git a/libraries/Error.class.php b/libraries/Error.class.php
index d332b06d7c..65fa1fc44d 100644
--- a/libraries/Error.class.php
+++ b/libraries/Error.class.php
@@ -158,7 +158,7 @@ class PMA_Error extends PMA_Message
                 $this->getMessage() .
                 $this->getFile() .
                 $this->getLine() .
-                $this->getBacktrace()
+                serialize($this->getBacktrace())
             );
         }