Thilanka,
with the same scenario, at the same point I now see:
Warning in ./libraries/common.lib.php#2917
Cannot modify header information - headers already sent by (output
started at server_privileges.php:1440)
Backtrace
./libraries/common.lib.php#2917: header(string Cache-Control: no-cache)
./server_privileges.php#2296: PMA_ajaxResponse(
object,
boolean 1,
array,
)