POST method not being called after OPTIONS - angularjs

Question

I'm trying to call an API from an angularjs application
var url = "...";
var myObject = {...};
var config = {
headers : {
'Content-Type': 'application/json;charset=utf-8;'
}
};
$http.post(url, myObject, config).then(function(result){...});
Because it's a cross-origin request, it does the preflight, so it calls the OPTIONS method.
This is the request header:
Host: ...
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Firefox/68.0
Accept: */*
Accept-Language: pt-BR
Accept-Encoding: gzip, deflate
Access-Control-Request-Method: POST
Access-Control-Request-Headers: content-type
Referer: http://localhost:9000/....
Origin: http://localhost:9000
DNT: 1
Connection: keep-alive
It returns as 200 OK, with the response header:
{
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS
Access-Control-Allow-Origin: *
Cache-Control: no-store, no-cache, must-revalidate
Content-Length: 0
Content-Type: text/html; charset=utf-8
Date: Fri, 01 Nov 2019 14:31:29 GMT
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Pragma: no-cache
Server: Microsoft-IIS/10.0
Vary: X-Requested-With
X-Frame-Options: GOFORIT
X-Powered-By: Nette Framework, ASP.NET
}
But it doesn't do the POST call afterwards. I tried calling the POST method directly through POSTMAN and it returned just fine. Is there something I'm missing?
EDIT: Heres the console error:
Possibly unhandled rejection:
{
"data":null,
"status":-1,
"config":{
"method":"POST",
"transformRequest":[null],
"transformResponse":[null],
"jsonpCallbackParam":"callback",
"headers":{
"Content-Type":"application/json;charset=utf-8;",
"Accept":"application/json, text/plain, */*"
},
"url":"...",
"data":{...},
"cached":false
},
"statusText":"",
"xhrStatus":"error"
}

Answer 1

The OPTIONS request has these headers set:
Access-Control-Request-Method: POST
Access-Control-Request-Headers: content-type
so it is asking whether it can do a POST request including the "content-type" header.
The server responds with:
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS
Access-Control-Allow-Origin: *
but it missing "Access-Control-Allow-Headers" response header:
Access-Control-Allow-Headers: content-type
Add this to the OPTIONS response and you should be good.
Possible, the error message in the console is
Reason: missing token ‘content-type’ in CORS header ‘Access-Control-Allow-Headers’ from CORS preflight channel*
which is self-explanatory.

Answer 2

add the additional header to your web.config like so...
<httpProtocol>
<customHeaders>
<add name="Access-Control-Allow-Origin" value="*" />
<add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS" />
<add name="Access-Control-Allow-Headers" value="Origin, X-Requested-With, Content-Type, Accept" />
</customHeaders>
</httpProtocol>