SE Eventsource Asp.net Core 3.1

[Hemalathaerdster]

[ApiController]
[Route("/SSE/[action]")]
public class SSEController : Controller
{
private static ConcurrentBag clients;
static SSEController()
{
clients = new ConcurrentBag();
}
[HttpPost]
public async Task SSECallbackMsg()
{
await CallbackMsg("test");
}
private async Task CallbackMsg(string test)
{
foreach (var client in clients)
{
try
{
var data = string.Format(test);
await client.WriteAsync(data);
await client.FlushAsync();
client.Dispose();
}
catch (Exception)
{
StreamWriter ignore;
clients.TryTake(out ignore);
}
}
}
[HttpGet]
public HttpResponseMessage GETSubscibe()
{
HttpResponseMessage response = new HttpResponseMessage();
response.Content = new PushStreamContent((a, b, c) =>
{ OnStreamAvailable(a, b, c); }, "text/event-stream");
return response;
}

private void OnStreamAvailable(Stream stream, HttpContent content,
    TransportContext context)
{
    var client = new StreamWriter(stream,Encoding.UTF8);
    clients.Add(client);
}

}
Javascript Method of calling above is like

function listenForServerEvents() {
var source = new EventSource('https://localhost:5002/SSE/GETSubscibe');
source.addEventListener("open", function (event) {
console.log('onopen');
}, false);
source.addEventListener("error", function (event) {
if (event.eventPhase == EventSource.CLOSED) {
source.close();
}
}, false);
source.addEventListener("message", function (event) {
console.log('onmessage: ' + event.data);
}, false);
}
when executing, above js function, i am getting error as EventSource's response has a MIME type ("application/json") that is not "text/event-stream". Aborting the connection.

Should add anything in startup.cs or is there any mistake., If anyone knows ,kindly help