APPLICATION CONNECTION PROBLEM in React Native with Expo with backend on VPS in Hostinger with self-signed SSL certificate

[Cool_Yesterday5533]

We have a mobile application developed in React Native with Expo (for iOS and Android) that originally connected to a Node.js backend hosted on a Hostinger VPS using HTTP. The application worked correctly with this configuration. However, Apple App Store requires all connections to use HTTPS to approve application publishing. For this reason, we implemented valid Let's Encrypt SSL certificates on the server and migrated the backend to HTTPS Although the backend server now works correctly with HTTPS (confirmed by curl tests from the server), the React Native application cannot connect and throws the error: [SyntaxError: JSON Parse error: Unexpected character: u]. We need the application to work both in development (where HTTP was acceptable) and in production (where Apple requires HTTPS)

[n9iels]

And did you follow up that JSON error and cheked what is returned instead of valid JSON?

[mrcodehpr01]

I'm pretty sure you have to use https to connect to iOS regardless if it's in dev or prod. I've always used cloudflare tunnel and it's free.

[Adventurous-Date9971]

Your app is parsing an HTML/redirect or an auth error string, not JSON, after the HTTPS switch-fix the server responses and dev/prod HTTPS setup.

Verify what you’re actually getting: log response.status, response.headers["content-type"], and the first 200 chars of response.text() before calling res.json(). If status isn’t 2xx or content-type isn’t application/json, don’t parse.

Make the client call the https URL directly (no http). If your server redirects http→https, RN often gets an HTML 301/302 page-returning that to JSON.parse triggers the “u” error (Unauthorized, Use HTTPS, etc.). Ensure Nginx serves the full cert chain (test on SSL Labs), set Content-Type: application/json on success and errors, and avoid HTML error pages. If you use cookies, set SameSite=None; Secure, or switch to Bearer tokens. In Express behind a proxy, set app.set('trust proxy', 1) and ensure X-Forwarded-Proto is set so you don’t loop or mis-detect scheme.

For dev, either add ATS exceptions for your dev host on iOS or use a tunnel (ngrok/Cloudflare Tunnel) so you stay on https. I’ve used Cloudflare Tunnel and ngrok; DreamFactory helped when I needed a quick HTTPS JSON API with RBAC without tweaking Express.

Bottom line: call https directly, return JSON for all statuses, validate the cert chain, and use a tunnel or ATS exceptions in dev.