Auth.js · browser URL

OAuthAccountNotLinked

/login?error=OAuthAccountNotLinked

What it means

Someone already has an account with this email, created with a different sign-in method (say, a magic link), and now tries GitHub. For security, Auth.js won't attach the new provider to an existing user who isn't signed in.

Common causes

• Same email used with email magic link first, GitHub second (or the reverse)
• Test users left in your dev database

How to fix it

1. Show a friendly message on your sign-in page: "Sign in the way you did the first time"
2. Let signed-in users link extra providers from their account page
3. allowDangerousEmailAccountLinking: true on a provider turns on auto-linking. Only use it if you trust that provider to verify emails

const messages: Record<string, string> = {
  OAuthAccountNotLinked: "That email already has an account. Sign in the way you did the first time.",
  Verification: "That sign-in link expired or was already used. Request a new one.",
};

Prompt for Cursor or Claude Code

Users who signed up with a magic link get OAuthAccountNotLinked when they try GitHub. Show a clear message for ?error=OAuthAccountNotLinked on my sign-in page. Don't enable allowDangerousEmailAccountLinking unless I confirm.

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