Firebase Cloud Functions https.onCall finished with status code: 204

Firebase Function

const functions = require('firebase-functions');
const admin = require('firebase-admin');
const cors = require('cors')({ origin: true });

exports.addMessage = functions.https.onCall((data, context) => {
  return { text: "Test" };


The problem is when i call this function from the app i first get finished with status code: 204 and after that finished with status code: 200


How can i prevent this?

This is normal, and you shouldn’t do anything to prevent it. The first request that results in 204 is what happens when CORS performs a preflight request. The 200 is the final serviced request.

You can read more about that here:

Two calls on Post request: with http 204 and 200

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