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

Question

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" };
});

Issue

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

204

How can i prevent this?

score 28 · Accepted Answer · answered Apr 19 '18 at 23:17

28

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

answered Apr 19 '18 at 23:17

Doug Stevenson

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Does this mean an .onCall takes 2 function executions from your quotum? – Jaap Weijland Feb 13 '19 at 21:57
3

@JaapWeijland Yes, when adding cors support, this is the case for both callable and regular HTTP functions. – Doug Stevenson Feb 13 '19 at 23:32
1

@DougStevenson, strange, I don't have any CORS and yet I am getting this. it's a simple vanilla onCall function – TheeBen Jul 20 '19 at 22:44
@TheeBen CORS is default in most browsers. It's actually harder to disable it. – nicolasassi Mar 04 '20 at 20:19

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

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