2👍
As long as you are running into the error callback your ajax request fails, most likely your backend fails.
Make sure that you’re ajax request is really working, I suggest postman, but you can also use cUrl:
curl 'http://yourhosthere/OgrenciSayilari.asmx/getOgrenciSayilari'
-H 'Pragma: no-cache'
-H 'Cache-Control: no-cache'
-H 'Accept-Encoding: gzip, deflate'
-H 'Content-Type: application/json; charset=UTF-8'
-H 'Accept: application/json, text/javascript, */*; q=0.01'
-H 'X-Requested-With: XMLHttpRequest'
--data-binary '{"gData":[]}'
Source:stackexchange.com