Heyy, We have a nest.js application deployed on Railway. In the frontend we have next.js deployed on Vercel. In the backend CORS is set like this

app.enableCors({
    origin: [
      '*',
      'http://localhost:3001',
      'http://localhost:3000',
      'https://*.vercel.app',
      'https://*.vercel.app/*',
    ],
    allowedHeaders: ['content-type', ...supertokens.getAllCORSHeaders()],
    credentials: true,
  });

But for all the vercel preview builds, we can't test the app because of CORS issues. Any Idea how to fix it.??

Hey @rayhan_rahat

Here is the options API headers

Hmmm. That’s odd

Okay there was two preflights, one passed, one failed, and actual request gets CORS errored

Is the supertokens middleware before or after the cors?

Before

Move the supertokens middleware to after the cors one and try again

nope. doesn't work. I think supertokens doesn't have proper support for vercel's dynamic url's I can only test on production/non-dynamic urls

That warning has nothing to do with cors setting issues

Ahh.. 😐 okay

So you should see why the cors isnt applied before the middleware runs

okay lemme try some things