Common Issues auth

Login or Signup Not Working in My AI App

Users try to log in or create an account but nothing happens, they get an error, or they're stuck in a loop. This is one of the most common issues with AI-generated apps because auth involves multiple moving parts.

Error Messages You Might See

Invalid login credentials Email not confirmed User already registered Failed to fetch 401 Unauthorized Redirect URI mismatch
Invalid login credentialsEmail not confirmedUser already registeredFailed to fetch401 UnauthorizedRedirect URI mismatch

Common Causes

  • Auth provider (Supabase, Firebase, Auth0) is not properly configured
  • Redirect URLs are wrong — the app sends users to the wrong page after login
  • Session or token management is broken — users appear logged in but the app doesn't recognize them
  • Email confirmation is required but the emails aren't being sent
  • Row Level Security (RLS) policies are blocking access to user data

How to Fix It

  1. Open browser dev tools (F12) and check the Network tab during login — look for failed API calls
  2. Verify your auth provider's redirect URL matches your actual app URL
  3. Check if email confirmation is enabled and whether emails are being sent (check spam folder)
  4. If using Supabase, check RLS policies — they often block legitimate queries
  5. Make sure your auth provider's API keys are correct in your environment variables

Real developers can help you.

Luca Liberati Luca Liberati I work on monoliths and microservices, backends and frontends, manage K8s clusters and love to design apps architecture Meïr Ankri Meïr Ankri Full-stack developer specializing in React / Next.js / Node.js with 6+ years of experience. I've worked across various sectors including automotive (Reezocar/Société Générale), healthcare (Medical Link SaaS), and e-commerce (Glasman). I build web apps end-to-end, from architecture to production, with a focus on scalability, performance, and code quality. I also mentor junior developers and contribute to technical decisions and code reviews. zipking zipking I am a technologist and product builder dedicated to creating high-impact solutions at the intersection of AI and specialized markets. Currently, I am focused on PropScan (EstateGuard), an AI-driven SaaS platform tailored for the Japanese real estate industry, and exploring the potential of Archify. As an INFJ-T, I approach development with a "systems-thinking" mindset—balancing technical precision with a deep understanding of user needs. I particularly enjoy the challenge of architecting Vertical AI SaaS and optimizing Small Language Models (SLMs) to solve specific, real-world business problems. Whether I'm in a CTO-level leadership role or hands-on with the code, I thrive on building tools that turn complex data into actionable value. MFox MFox Full-stack professional senior engineer (15+years). Extensive experience in software development, qa, and IP networking. Anthony Akpan Anthony Akpan Developer with 8 years of experience building softwares fro startups David Olverson David Olverson Solo dev shipping production apps with AI-assisted development. I specialize in rescuing broken Lovable/Bolt/Cursor builds and taking them to production. 10+ apps shipped including SaaS CRMs, gaming platforms, real estate tools, and Discord bots. Stack: Next.js 16, TypeScript, Tailwind CSS, FastAPI, PostgreSQL, Prisma. I use Claude Code with 50+ custom skills for rapid delivery. Average turnaround: 2-4 weeks from broken prototype to production. Bastien Labelle Bastien Labelle Full stack dev w/ 20+ years of experience Costea Adrian Costea Adrian Embedded Engineer specilizing in perception systems. Latest project was a adas camera calibration system. legrab legrab I'll fill this later Caio Rodrigues Caio Rodrigues I'm a full-stack developer focused on building practical and scalable web applications. My main experience is with **React, TypeScript, and modern frontend architectures**, where I prioritize clean code, component reusability, and maintainable project structures. I have strong experience working with **dynamic forms, state management (Redux / React Hook Form), and complex data-driven interfaces**. I enjoy solving real-world problems by turning ideas into reliable software that companies can actually use in their daily operations. Beyond coding, I care about **software quality and architecture**, following best practices for componentization, code organization, and performance optimization. I'm also comfortable working across the stack when needed, integrating APIs, handling business logic, and helping transform prototypes into production-ready systems. My goal is always to deliver solutions that are **simple, efficient, and genuinely useful for the people using them.**

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Frequently Asked Questions

Users can sign up but can't log in. What's wrong?

Usually an email confirmation issue — check if your auth provider requires email verification. Also verify that the login redirect URL is correct.

Login works on localhost but not in production. Why?

Your auth provider's redirect URLs probably still point to localhost. Update them to your production domain in the auth provider's dashboard.

Related Common Issues Issues

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