IIS fails POST request from Arduino but accepts the same from HTTP client/terminal

Hello everyone I have a problem that is driving me insane.

Yesterday evening I was sending data from my arduino to my cloud service on azure (Nancy Restful webservice)and debugging it, I could hit the breakpoint, browsing the request, and see everything. However I was sending the data wrong and binding it wrong, so i could not see the data. Then today I fixed it but when I tried to redebug my cloud service sending data from the arduino, I wasn't working any longer. It totally ignores the arudino POST requests and cannot hit the breakpoint. but from POSTMAN in chrome, or terminal it works fine. :?

I tried looking at the failed request and there are a bunch saying

ModuleName
ManagedPipelineHandler 

Notification
EXECUTE_REQUEST_HANDLER 

HttpStatus
500 

HttpReason
Internal Server Error 

HttpSubStatus
0 

ErrorCode
The I/O operation has been aborted because of either a thread exit or an application     request.
(0x800703e3) 

ConfigExceptionInfo

 ManagedPipelineHandler

Anyone have any idea what happened? ( I was in school and redeployed a couple of time but only changed some code in the backend about the binding, no configuration etc). I am loosing my mind over this.. :/