Supabase Auth errorSupabase Auth: identity_already_exists

Rather not fix it yourself? App Fix Ticket starts with a fixed-price diagnosis, then a fixed price for the fix before any fix work.

Why the identity can’t be linked, and the fix

1. 01

   The OAuth account already belongs to another user

   “The identity to which the API relates is already linked to a user.” Supabase docs, Auth error codes (identity_already_exists)

   The user signed up earlier with that Google account, then signed up again with email. Linking can’t move an identity between users; sign in with it, or unlink it from the old user first.

   const { data, error } = await supabase.auth.linkIdentity({ provider: 'google' });
   // After the redirect, look for error_code=identity_already_exists in the URL query string or hash
   // and offer: 'This Google account already has an account. Sign in with it?'

2. 02

   The identity was already linked automatically

   “Supabase Auth automatically links identities with the same email address to a single user.” Supabase docs, Identity linking (Automatic linking)

   Supabase links OAuth identities with the same email to one user. A user who signed in with Google using the same email may already have it. Check getUserIdentities before showing a link button.

3. 03

   Unlinking fails on the other account

   “The user needs to be signed in and have at least 2 linked identities in order to unlink an existing identity.” Supabase docs, Identity linking (Unlink an identity)

   An account with only one identity can’t drop it, or the user would be locked out. Add an email and password or another provider to that account first, then unlink.

4. 04

   Manual linking is off

   “Calling the supabase.auth.linkUser() and related APIs is not enabled on the Auth server.” Supabase docs, Auth error codes (manual_linking_disabled)

   Also check: linkIdentity needs manual linking turned on. With it off, the error is manual_linking_disabled rather than this one.

Checked against the vendor’s docs on November 9, 2026: Supabase docs: Auth error codes; Supabase docs: Identity linking.

Rather hand it over?

Fixed scope, fixed price, paid upfront. The work happens in writing; no call needed.

• from $450App Fix TicketOne reproducible bug in an existing mobile or web app, diagnosed and fixed.See scope and start
• from $450AI-Built App RescueA Lovable, Bolt or Cursor app checked end to end in 3 days, then its worst problems fixed at a fixed price.No issues worth fixing, no charge. If the Launch Check finds nothing rated medium or higher, Simon refunds the full $450. You keep the report either way. This applies to the first 10 Launch Checks bought after October 30, 2026.See scope and start

Related: Supabase user already registered · Supabase OAuth provider disabled · Supabase Auth session missing · Supabase Storage resource already exists