401 Error: Causes, Impacts and Solutions to Resolve “Unauthorized”

The 401 error, also known as "Unauthorized", occurs when access to a resource is denied due to missing authentication or incorrect credentials. This error can frustrate users, harm the customer experience and cause technical problems for your site.

In this article, we'll cover:

• What the HTTP 401 error is.
• The main causes of this error.
• The solutions for fixing the 401 error.
• Best practices to keep it from happening again.

Need help with other errors? Check out our complete guides on the HTTP errors 404, 500, 403, 502, 504, 429, 400 and 410 to understand their causes, impacts and solutions.

What is the 401 error?

The HTTP 401 error means that the user or agent (such as a browser or a bot) hasn't provided valid credentials to access a resource. Unlike a 403 error (Forbidden), this error means that authentication is required and was either not provided or is incorrect.

Common appearances of the HTTP 401 error:

• 401 Unauthorized
• HTTP Error 401 – Unauthorized
• Access Denied – Authentication Required
• 401 Error – Restricted access

Why is fixing the HTTP 401 error important?

Impact on the user experience:

• Visitors often don't understand why access is being denied to them, which frustrates them and may make them leave the site.
• Authenticated users risk losing trust if their credentials don't work properly.

Impact on SEO:

• Search engines like Googlebot may encounter this error while crawling, which prevents the indexing of the affected pages.
• If this error is widespread across your site, it can hurt your SEO ranking.

Useful resources:

• Learn more about the impact of HTTP errors in the official Google Developers documentation.
• Discover how search engines interpret these errors on the Moz site.

Common causes of the HTTP 401 error

No authentication:

• The user hasn't provided the credentials required to access the resource.

Incorrect credentials:

• The username or password provided is incorrect.

Issues with bots or crawlers:

• If bots or Googlebot send too many requests at a fast pace, the server may block those requests.

Expired authentication token:

• In the case of an API or a web application, the authentication token or session may have expired.

Server configuration problems:

• A misconfiguration of the web server or of the .htaccess files can prevent access.

Conflicts with plugins or extensions:

• In WordPress, for example, certain security or authentication plugins can cause conflicts.

How do you fix the 401 error?

1. Check your access credentials:

• Make sure the username and password are correct. If necessary, reset the credentials for the affected users.

2. Test the server permissions:

• Check the server configuration files (such as .htaccess or nginx.conf) to make sure the permissions are set up correctly.

3. Reset or renew the authentication token:

• If you're using an API or a web application, make sure the access token hasn't expired. If it has, generate a new token.
• See the complete guide to authentication via OAuth on oauth.net.

4. Temporarily disable plugins or extensions:

• If you're using WordPress or another CMS, disable the plugins related to authentication or security to identify a possible conflict.

5. Set up a custom authentication page:

• A user-friendly page that guides users in providing their credentials can improve the user experience.

6. Check the API configurations:

• The server logs can provide details about the exact cause of the 401 error.
  – Apache: /var/log/apache2/error.log
  – Nginx: /var/log/nginx/error.log

Best practices to avoid the HTTP 401 error

1. Simplify authentication for users:
   – Offer options such as social login or single sign-on (SSO).
2. Monitor user sessions:
   – Set reasonable session durations to keep users from being logged out unexpectedly.
3. Keep your plugins and extensions up to date:
   – Outdated versions can cause conflicts or security issues.
4. Implement secure authentication:
   – Use protocols such as OAuth 2.0 or HTTPS to protect credentials.
5. Regularly test your authentication processes:
   – Simulate scenarios where users provide incorrect credentials to make sure 401 errors are handled correctly.

To go further:

• Discover tips on managing secure access with the Sucuri Security guide.

Conclusion

The HTTP 401 error may seem intimidating, but it's usually easy to fix once you understand its causes. By checking your authentication configurations and following the steps I've shared with you, you'll be able to resolve this problem quickly.

To keep this error from happening again, follow the best practices mentioned and regularly monitor errors via Google Search Console. If you'd like to learn more about other HTTP errors, explore my articles on the errors 404, 500, 403, 502, 503, 504, 429, 400 and 410 for detailed solutions!