No account linked to this provider
Product text: no account is linked to this social provider — register first or sign in with email and password (auth.oauthNoLinkedAccount).
Why this happens
The OAuth identity is not linked to an existing member, and the flow expects an existing link (or registration is not creating one). This locale string may appear as a legacy/orphan message; active redirects more often use Account not found / registration-disabled / email-already-registered codes. Treat the user-facing advice the same: establish an account, then link the provider.
Diagnose and fix
1. Register with email/password (or complete social register if open), then sign in.
2. Sign in with email/password first; link the provider from Social login (member view) if available.
3. Admin: ensure Social login + registration are open as intended.
4. Distinct from Invalid or expired sign-in session — try again (state/cookie problem mid-flow).