Why is authentication suddenly broken?
Last checked 31 Aug 2026
Short answer
Auth usually breaks after a schema change, an RLS policy edit, or an expired/misconfigured provider setting — check Logs first, then ask Lovable to diagnose before fixing.
Start with the logs
Open the Logs panel (auth section) and reproduce the failed sign-in. Look for the exact error: expired token, redirect URL mismatch, RLS denial, or a missing table/column after a recent change.
Common causes
- A recent database change removed or renamed a column the auth flow depends on (e.g. a
profilestrigger that inserts a row on signup). - Row-level security was tightened and now blocks the row a new user needs to read on login.
- Redirect/site URL settings changed — common after connecting a custom domain or renaming a project.
- Role logic on a profile column instead of a separate
user_rolestable, which breaks in confusing ways once policies reference it. - Third-party auth provider (Google, GitHub) credentials expired or the redirect URI no longer matches.
Diagnose before touching anything
Ask Lovable to investigate without changing code first, so you don't stack a bad fix on top of the real bug:
Authentication is failing for new sign-ups. Check the auth logs and the database trigger/policies involved, tell me the root cause, and don't change any code yet.
Fix in small steps
- Confirm the diagnosis matches the log error.
- Ask for the smallest possible fix — a single trigger, policy, or redirect URL — rather than a broad "fix auth" prompt.
- Test sign-up, sign-in and sign-out again in Preview after each change.
- Use Version history to revert instantly if the fix makes things worse.
What usually goes wrong
People ask Lovable to "fix authentication" in one vague prompt, which can trigger a large rewrite of unrelated auth code. Be specific about the symptom (which step fails, what error shows) and point at the likely area (trigger, policy, provider settings). If the project uses Lovable Cloud, remember you can't check things in a Supabase dashboard yourself — ask Lovable to inspect the backend for you.
If the cause isn't obvious after a couple of rounds, a second pair of eyes from PromptSites.com can save hours of guesswork.
Sources
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