Vercel preview deployment returns 403 but production works

[hongsonit10-6125 (Jason Nguyen)]

Hi team,

My Vercel project has an issue where Preview Deployments return 403 Forbidden, but the production domain works normally.

I’ve verified:

• No auth/middleware blocking routes

• Code works fine (tested even with a fresh Vite React app)

• No vercel.json rules affecting preview

• Production deployment is OK

This seems specific to Preview Deployments only.

Any idea what could cause this?

Thanks.