android – What is the `Authorization` part of the http post request of Google's Firebase Downstream message?-ThrowExceptions

Exception or error:

I want to try to send a message using google’s FCM messaging service and as the document says, the http request should be something like this:

{ "data": {
    "score": "5x1",
    "time": "15:10"
  "to" : "bk3RNwTe3H0:CI2k_HHwgIpoDKCIZvvDMExUdFQ3P1..."

My problem is that I have not idea what Authorization‘s value should be and when I delete this header and make the request, I get error 401:Unauthorized.I think this must be some kind of api key or something but I cannot find it in my project. Can anyone help me?

PS: for testing purposes I currently am using this site to send a messsage to my device

How to solve:

According to About Firebase Cloud Messaging Server documentation:


To send a message, the app server issues a POST request. For example:

A message request consists of two parts: the HTTP header and the HTTP

The HTTP header must contain the following headers:

  • Authorization: key=YOUR_SERVER_KEY

    Make sure this is the server key, whose value is available in your Firebase project console under Project Settings > Cloud Messaging. Client keys or any other keys are rejected by FCM.

  • Content-Type: application/json for JSON; application/x-www-form-urlencoded;charset=UTF-8 for plain text.

    If Content-Type is omitted, the format is assumed to be plain text.

Hope it helps!

UPDATE (2016/11/16)

Perhaps you should consider using the FCM token instead of the server keys as the note inside the following screenshot

enter image description here

UPDATE (2016/12/08)

Firebase has upgraded the server keys to a new version and recommended that you upgrade to the newest version. Please see the screenshot below:

enter image description here


i have also faced this error. The issue is with the server key. Don’t use the api key from google-services.json file.

You should use the server api key from your firebase console project, at the cloud messaging tab project keys:


This is your Server key which you can observe into or Firebase project console under Project Settings > Cloud Messaging. Note the key it’s auto created by Google Services. You ought add IP Address inco G.Console to restrict usage.

Plus do remember about Content-Type: application/json, otherwise you will get Error=MissingRegistration.

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