Fix user sessions that disappear or reset
Session persistence issues cause users to lose their login state between page navigations or refreshes. This is typically caused by misconfigured cookies, incorrect SameSite attributes, or the session store losing data.
Error messages you might see
Error: Session not found or expiredWarning: connect.session() MemoryStore is not designed for a production environment.Why this happens in AI-generated code
Using in-memory session storage in production
AI-generated Express/Next.js code uses the default MemoryStore for sessions, which loses all sessions when the server restarts or scales to multiple instances.
Cookie configuration incorrect for production
AI tools set cookie options for localhost (no Secure flag, SameSite=Lax) that don't work in production where HTTPS and cross-site navigation require different settings.
Session cookie domain mismatch
AI-generated code hardcodes the cookie domain or doesn't set it, causing the browser not to send the session cookie when the domain changes between environments.
How to fix it
Use a persistent session store
Replace MemoryStore with Redis, a database, or your hosting provider's session storage. This ensures sessions survive server restarts and work across multiple instances.
Configure cookies correctly for your environment
Set Secure: true for HTTPS, SameSite: 'lax' for most cases, and ensure the cookie domain and path match your application's URL. Use environment-specific cookie config.
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Frequently asked questions
Should I use cookies or localStorage for sessions?
Use httpOnly cookies for session tokens — they're automatically sent with requests and can't be accessed by JavaScript, protecting against XSS. localStorage is vulnerable to XSS and requires manual header management.
Why does my session work on one page but not another?
Check your cookie path configuration. If the cookie path is set to '/api', it won't be sent for requests to '/dashboard'. Set the path to '/' to ensure the cookie is sent for all routes.
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