All Shards failed to assign

Thanks @Steve_Mushero
I have issue in my index mapping mapping and i found the right index mapping to fix this. When i tried to update index mapping into my Elastic search but i am getting "Validation Failed: 1: mapping type is missing;

I am using this PUT API to update index mapping:
http://dev.com/my_index/_mapping

Request json i am using the response i recieved from
GET http://dev.com/my_index/_mapping

May be my request is not correct please let me know how to construct the right request for this update index mapping API and i am using ES version 5.6.5

Thanks,
Pradeep