Handling TypeScript Errors in NextAuth

When integrating NextAuth into your Next.js application, you may encounter TypeScript errors, particularly the message: Type error: Property 'session' does not exist on type '{}'. This guide will help you resolve this issue by correctly defining your application types.

Step 1: Define Custom App Props

To begin, you need to extend the default AppProps interface to include the session property. This allows TypeScript to recognize the session object when passed to your custom app component.

import { AppProps } from 'next/app';
import { Session } from 'next-auth';

// Extend the default AppProps to include session
export interface CustomAppProps extends AppProps {
  Component: React.ComponentType & { auth?: boolean; session?: Session };
}

Step 2: Implement the MyApp Component

Next, implement your custom MyApp component. Ensure that you destructure the session from pageProps correctly. This is crucial for passing the session to the SessionProvider component.

import { SessionProvider } from 'next-auth/react';
import { CookieConsentProvider } from 'your-cookie-consent-library';

function MyApp({ Component, pageProps }: CustomAppProps) {
  return (
    <>  
      <CookieConsentProvider useCookieConsentHooksOptions={{ consentCookieAttributes: { expires: 360 } }}>
        <SessionProvider session={pageProps.session}>
          <Component {...pageProps} />
        </SessionProvider>
      </CookieConsentProvider>
    </>
  );
}

Step 3: Verify TypeScript Configuration

If you continue to see the TypeScript error, double-check your TypeScript configuration. Ensure that your tsconfig.json is set up to include the necessary types and that there are no conflicting types defined elsewhere in your code.

Conclusion

By following these steps, you should be able to resolve the TypeScript error regarding the session property in your NextAuth configuration. This setup not only ensures type safety but also enhances the maintainability of your code.

For more detailed information, refer to the NextAuth documentation.