Hi, SENTHILKUMAR.
How exactly do you send that request to `/end_session`? Please note you must include `session_id` in it, either via cookies, or in url query string's parameter with the same name. So, for example, if your request is sent by a backend service (we had such case reported recently), it may not be in possesion of this id and such request will fail.
If you don't include `session_id` in query string, please make sure that at least you include all cookies issued by oxAuth for the session in question.