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[Vue.js] CORS policy No 'Access-Control-Allow-Origin' / 500 (Internal Server Error) Problemcontroller codeclient code

Basically, I’m trying to get a username by id from Sequelize. The problem is that when either stuck with a CORS problem or 500 Internal Server error depending on the response(status)

cors and 500

controller code

async getUserFromUserId (req, res) {
try {
// const user = await User.findByPk(
const id =
const user = await User.findByPk(id)
} catch (err) {

// or res.status(some random number).send() for CORS problem to appear

error: ‘an error has occured trying to fetch the users id’

client code

this.notifiedUser = (await UserService.getUserFromUserId({id: UserId})).data

I get a Status: 200 OK from postman though.
Postman Solution

there is seen how the other Solution for the cors thingy, but the solutions does not specify as to why I get “undefined” results after resolving the cors problem.

Solution :

So, CORS is actually really obnoxious in this regard, but there’s a fairly straightforward way to fix this. It’s a super useful security feature, though it is frustrating at best sometimes.

the browser does what is called a Preflight Request, which is of the http verb OPTIONS. the browser calls whatever route you want, but instead of what you asked it to do, it calls using OPTIONS first. the server should accept all routes that the client can ask for with the OPTIONS method, and the server should respond with the following headers to be an externally available, cross-origin API.

Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, …

(note, you should not put the … in, but you can put any HTTP verb in this list)

If you require the own headers (for auth purposes), you want to add this header for Client -> Server.

Access-Control-Allow-Headers: YourHeader, YourHeader2, YourHeader3

You want to add this one for Server -> Client

Access-Control-Expose-Headers: YourHeader,YourHeader3

Note that the OPTIONS call is an entirely separate call that you should handle as well as the GET method.

You’ve now told the browser what it is allowed to ask for, and what it can expect to get back from the API. If you don’t respond to the OPTIONS request, the browser terminates the request, resulting in a CORS error.

I’m going to take a gander at a guess and assume you’re likely using Express, which this answer describes how to set the headers on.

What do the headers mean, in English?

From where are clients allowed to access this resource (endpoint)? This can match partial domains with wildcards, or just a * to allow anywhere.

What HTTP methods are permissible on this route?

When I get a response from the server, what should I (the browser) expose to the client-side?

What am I as the client side allowed to send as headers?

Solution 2:

If the origin is from localhost, Chrome usually blocks any CORS request originating from this origin.

You can install this extension:

Or you can disable the security when running chrome (add the flag):