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#[next-auth][error][CLIENT_FETCH_ERROR]
calm novaBOT
The error you're encountering is a CLIENT_FETCH_ERROR in NextAuth.js, which typically occurs when there's an issue with the API response during authentication. The error message indicates that the response contains HTML (starting with "<!DOCTYPE") instead of the expected JSON format.
Common Causes and Solutions
This error often happens for several reasons:
-
Server-side error handling issues: When using NextAuth.js with server components in Next.js, error handling can be problematic, especially in production builds.
-
Middleware compatibility issues: Using bcrypt or argon2 in middleware or edge runtime environments can cause problems, as seen in your code with argon2.
-
Response format issues: The server is returning HTML instead of JSON, which could be due to an error page being rendered instead of a proper API response.
Recommended Fixes
Based on the knowledge sources, here are some solutions:
-
Move password verification to a separate API route:
One solution is to create a separate API endpoint for password verification and call it from your authorize callback. This approach is mentioned in this GitHub issue where users faced similar problems with bcrypt.
// Create a separate API route for verification
// Then in your authorize callback:
async authorize(credentials) {
// Validate credentials
if (!credentials?.email || !credentials?.password) {
return null;
}
// Call your verification API instead of using argon2 directly
const response = await fetch(`${process.env.API_URL}/verify-password`, {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({
email: credentials.email,
password: credentials.password
}),
});
if (response.ok) {
const user = await response.json();
return user;
}
return null;
}
-
Improve error handling:
Instead of throwing errors, return null with proper error handling:
async authorize(credentials) { try { // Your verification logic if (!credentials?.email || !credentials?.password) { console.log('Missing credentials'); return null; } // Rest of your code } catch (error) { console.error('Authentication error:', error); return null; } } -
Check for Edge Runtime issues:
If you're using Edge Runtime, be aware that certain libraries like bcrypt and argon2 aren't compatible. As mentioned in this GitHub issue, you might need to use a different approach for password verification in Edge environments.
Additional Considerations
- Make sure your NextAuth configuration is in the correct location according to your Next.js version
- Verify that your environment variables (NEXTAUTH_JWT_SECRET, NEXTAUTH_SECRET) are properly set
- Consider using the beta version of NextAuth (v5) if you're using Next.js 14, as it has better integration with App Router
The error suggests that your server is returning HTML instead of JSON, which often happens when there's an unhandled server-side error. By improving your error handling and potentially moving password verification to a separate endpoint, you should be able to resolve this issue.