Get 403 response with the "new" Firebase Cloud Messaging API

Question

We are successfully using the Legacy HTTP Server Protocol on our server for FCM. I wanted to update to FCM HTTP v1 API today.

I did it step by step and when the server calls the request, we get this response:

Server returned HTTP response code: 403 for URL: https://fcm.googleapis.com/v1/projects/[projectid]/messages:send

This is the server code:

URL url = new URL("https://fcm.googleapis.com/v1/projects/[projectid]/messages:send");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty("Authorization", "Bearer " + getAccessToken());
conn.setRequestProperty("Content-Type", "application/json");
OutputStream outputStream = conn.getOutputStream();
outputStream.write(req.getBytes("UTF-8"));

// Exception happen here
InputStream inputStream = conn.getInputStream();

The getAccessToken():

private static String getAccessToken() throws IOException {
        GoogleCredential googleCredential = GoogleCredential
            .fromStream(new FileInputStream(ClientApiServlet.context.getRealPath("/WEB-INF/[projectid].json")))         .createScoped(Arrays.asList("https://www.googleapis.com/auth/firebase.messaging"));
        googleCredential.refreshToken();
        return googleCredential.getAccessToken();
}

I have downloaded the json file from the adminsdk page of the firebase cloud.

All with the same projectid...

I updated these 2 libs on the server:

google-http-client-jackson2-1.23.0.jar
google-oauth-client-1.23.0.jar

The getAccessToken() methode returned an accesstoken: "ya29.c.Elr0BAa..."

I think, I miss a small step, maybe you could help? Thanks in advance!

Edit: It is working now with the hint of arterpa! Thanks again!

After that I got a 400 error, so something in the request data was wrong:

The problem was, we didn't converted all data{...}values to strings. With the legacy protocol it was not an issue, but with FCM HTTP v1 API it has to be strings! ;)

Answer 1

I had this problem, and it seems you need to enable FCM API for your project at Google API console.