Update: remove static (method is private anyway and will be called once)

lib/Doctrine/DBAL/Driver/Mysqli/MysqliConnection.php

@@ -176,7 +176,7 @@ class MysqliConnection implements Connection
             $supportedDriverOptions[] = \MYSQLI_SERVER_PUBLIC_KEY;
         }
 
-        static $exceptionMsg = "%s option '%s' with value '%s'";
+        $exceptionMsg = "%s option '%s' with value '%s'";
 
         foreach ($driverOptions as $option => $value) {