UnityWebRequest with "text/event-stream" header doesn't work in webgl build


I am trying to implement a request to firebase, which follows server side events protocol. It looks like this:

using System.Collections;
using UnityEngine;
using UnityEngine.Networking;

public class Test : MonoBehaviour
    public IEnumerator TestCoroutine()
        string databaseSecret = "DATABASE_SECRET";
        string firebaseHost = "https://your-firebase-project.firebaseio.com";
        UnityWebRequest req = UnityWebRequest.Get(firebaseHost + "/.json?auth=" + databaseSecret);
        req.SetRequestHeader("Accept", "text/event-stream");
        var response = req.SendWebRequest();
        while (!req.downloadHandler.isDone)
            Debug.Log("Text downloaded: " + req.downloadHandler.text);
            yield return new WaitForSeconds(1);
    // Use this for initialization
    void Start()

It works fine in editor, but no data is received in webgl build. With webgl build I can see in browser dev tools that the request is made, and that it continues running, so req.downloadHandler.isDone is false, however both req.downloadHandler.text and req.downloadHandler.data are always empty.
I tried using wireshark to see if any data is passed and I observed that there are new chunks of data when the server side event is triggered by me, using another device, but it’s hard to tell what this data represents - its not readable.

I wanted to know if I am doing something wrong, of it is a bug or if it is a limitation of webgl. I would appreciate suggestions on workaround. Thanks!

Did you ever get this to work? Like everyone else asking this question, I’d love to have firebase RTDB streaming data working in Unity WebGL builds.