Microsoft Edge and _JS_WebRequest_Create Exception

Unity Engine
1

We have a WWW request that executes perfectly in Firefox and Chrome, however throws an exception in Microsoft Edge and IE 11.

The WWW request is sending data to an external .net service hosted on IIS7, so I’m guessing the answer is there, however I am not able to find a solution or explanation as to why.

exception thrown: Error: Access is denied.
,Error: Access is denied.

at _JS_WebRequest_Create (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:1:208892)
at FLc (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:17:661426)
at Vcb (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:12:958045)
at S$b (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:19:156521)
at R4i (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:6:865892)
at S4i (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:6:865973)
at Skf (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:7:762447)
at $$j (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:8:566079)
at gTk (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:24:180971)
at invoke_iiii (blob:27587F30-10AF-4163-963C-BF8304AF9AF2:1:362780)
UnityLoader.js (1,31293)

Encoding encoding = Encoding.UTF8;
byte[] bytes = encoding.GetBytes(serialized);

Dictionary<string, string> headers = new Dictionary<string, string>();
headers.Add("Content-Type", "application/json; charset=utf-8");
       
WWW www = new WWW(URL, bytes, headers);

yield return www;
2

if you make a Development build, then you can open the generated js with a text editor and see the JS_WebRequest_Create implementation. Then you can log something to narrow down the function that throws the exception (perhaps XMLHttpRequest.open)