Error: next-auth route not found in Next.js: Causes and How to Fix

Potential Causes of Next-Auth Route Not Found Error

• Incorrect API Route Configuration: One of the most common causes of this error is incorrect setup of the API route handling authentication in a Next.js application. The default next-auth endpoint should typically be set up at `pages/api/auth/[...nextauth].js`. Any misplacement or misnaming of this file can lead to the route not being found.

 

• Improper Middleware Configuration: If middleware is incorrectly configured or missing necessary permissions/settings, the authentication routes may not be accessible, leading to the error. This can happen when modifying middleware configuration files or updating Next.js leading to deprecated functions.

 

• Not Including next-auth Session Provider: If a Next.js application fails to wrap components in the `SessionProvider` that comes with next-auth, it might cause route not found errors, since the authentication context won't be properly available across the application.

 

• Environment Variables Not Set: Missing or incorrect environment variables, such as those defining database URIs or authentication secrets, can cause route errors. This is crucial for setting up providers like OAuth or custom server configurations.

 

• API Route Not Exporting Properly: If your `[...nextauth].js` file doesn't properly export a default handler using `NextAuth`, the route may not recognize the correct handler and result in the error. Ensure the file ends with `export default NextAuth(authOptions);` where `authOptions` is properly defined.

 

// Example of a correctly implemented [...nextauth].js file
import NextAuth from 'next-auth';
import Providers from 'next-auth/providers';

const options = {
  providers: [
    Providers.Google({
      clientId: process.env.GOOGLE_ID,
      clientSecret: process.env.GOOGLE_SECRET
    })
    // Add more providers here
  ],
  // Optional settings
  secret: process.env.SECRET,
};

export default (req, res) => NextAuth(req, res, options);

• File System Restrictions: When hosting on file systems with case sensitivity or restrictions, like certain Linux distributions, ensuring the file naming conventions match exactly can prevent route not found issues.

 

• Lack of Compatible Provider Setup: Sometimes previous configurations with identity providers like Google, Facebook, etc., may not be directly compatible with updated library versions if not set up or updated correctly, leading to dynamic route errors.

 

• Integration Issues with Custom Frameworks: If your Next.js app is integrated with another framework or custom server solutions, and the routing is managed incorrectly, it might override next-auth's routes, causing them not to be found.