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

Question

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:

Answer 1

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: https://console.firebase.google.com/project/firebase-probiz/settings/cloudmessaging