Getting CORS-error when trying to use Ethers library

Hello! I’m getting a strange CORS error when I’m trying to invoke one of the cloud functions I created with Firebase. I have the following cloud function:

export const getUser = functions.https.onRequest(async (req, res) => {

    res.set("Access-Control-Allow-Origin", "http://127.0.0.1:5501"); 

    res.set("Access-Control-Allow-Headers", "Content-Type");

    console.log("getUser() function is invoked");

    const method = req.method;

    const body = req.body;

    const address = body.address;

    res.json({method: method, body: address});

    return;
});

(The function looks a little bit strange now perhaps but It’s just for testing invocation and reading the request message).

I’m invoking the function with the following code:

function runGetUser() {

    axios({

        method: 'POST',

        url: 'my_url',

        data: { "address": '0x8038494b070d0Fedf948bdF15a2580a99EFa7b47' },

    }).then((response) => {

        console.log(response.data);

    }).catch((error) => {

      console.log(error);

    });

};

And i’m getting the following response nicely:

{method: ‘POST’, body: ‘0x8038494b070d0Fedf948bdF15a2580a99EFa7b47’}

However, when I’m trying to use ethers library to make sure the address is converted to checksum before I’m doing anything else using the following code:

export const getUser = functions.https.onRequest(async (req, res) => {

    res.set("Access-Control-Allow-Origin", "http://127.0.0.1:5501"); 

    res.set("Access-Control-Allow-Headers", "Content-Type");

    console.log("getUser() function is invoked");

    const utils = ethers.utils;

    const method = req.method;

    const body = req.body;

    const address = body.address as any;

    const userAddress = utils.getAddress(address);

    res.json({method: method, body: userAdress});

    return;
});

, it’s throwing me the following error:

Access to XMLHttpRequest at ‘http://127.0.0.1:5001/cloud-functions-typescri-772a4/us-central1/user-getUser’ from origin ‘http://127.0.0.1:5501’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: It does not have HTTP ok status.
index.js:9 F {message: ‘Network Error’, name: ‘AxiosError’, code: ‘ERR_NETWORK’, config: {…}, request: XMLHttpRequest, …}
axios.min.js:1 POST http://127.0.0.1:5001/cloud-functions-typescri-772a4/us-central1/user-getUser net::ERR_FAILED

And I cannot understand why I would even get a CORS-error when I have only changed some logic inside the invoked function.

This only happens when you use ethers.js? What previous code works normally?