Learn

Resources to understand all relevant details about status codes and redirects.

401

Unauthorized


The 401 Unauthorized status code is an HTTP response status code that indicates the client attempting to access a resource has not provided valid authentication credentials for that resource. In other words, it signifies that the request lacks valid user authentication.

This means that the user is not authorized to access the requested resource and needs to provide valid login information or authentication tokens. This response typically occurs when trying to access a restricted page without providing valid login credentials.

Here are some key points about the 401 Unauthorized status code:

  • Authentication requirement: A server sends a 401 response when it requires authentication from the client to access a particular resource or perform a specific action.
  • Missing credentials: The 401 status indicates that the client must provide valid credentials (e.g., username and password) through an Authorization header or another appropriate method specified by the server.
  • Common causes:
    • Missing or incorrect authentication credentials: If the client provides authentication credentials, but they are incorrect or expired, the server will respond with a 401 status code. When accessing a secured webpage or API endpoint, if the client fails to provide valid authentication credentials (such as username/password, API key, token), it will result in a 401 response.
    • Missing required authorization headers: Sometimes, clients may forget to include necessary headers in their request for authentication purposes. This can result in a 401 response from the server.
    • Incorrect configuration of Basic Authentication headers: Basic Authentication requires sending appropriate Authorization headers containing Base64-encoded username and password combinations. If these headers are missing or improperly set up during communication between client and server, it can result in receiving a 401 response.
    • Session timeout: If a user's session expires due to inactivity or other factors, subsequent requests made by the user without re-authentication can lead to receiving a 401 status code.
    • Expired or revoked authentication token: If the provided authentication token has expired or been revoked due to security reasons, attempting to use it will lead to a 401 error.
  • Difference from 403 Forbidden: While both codes relate to denying access, a "401 Unauthorized" error suggests missing or invalid credentials for authentication purposes, whereas a "403 Forbidden" error indicates valid authentication but a lack of authorisation or permission to access the requested resource.
  • Handling responses: Clients should handle a returned 401 error by prompting for appropriate user authentication details and then resubmitting the request with correct credentials included in subsequent requests' Authorization header.
  • User experience: From a user experience perspective, encountering a 401 Unauthorized error can be frustrating. To mitigate this issue and improve user experience, it is important to handle authentication errors properly. Here are some recommendations:
    • Clear and informative error messages: Provide clear instructions on how users can resolve the error by either logging in again or providing correct credentials.
    • User-friendly login process: Make sure your login page is easy to use with clear fields for entering username/passwords and appropriate feedback if there are any issues.
    • Session management: Implement an automatic session timeout feature with appropriate warning notifications so that users do not unexpectedly encounter a 401 error due to their session expiring.
    • Remember me option: Provide an option for users to remain logged in across sessions using cookies or other persistent storage mechanisms.
    • Single Sign-On (SSO) integration: If applicable, implement SSO so that users only need to authenticate once across multiple applications or websites within your ecosystem.
    • Graceful handling of unauthorized requests: Redirect users back to a relevant page after successful authentication rather than showing them an empty "Unauthorized" message page.
    By implementing these measures, you can enhance usability while dealing with 401 Unauthorized errors and minimize frustration for your users when accessing protected resources on your website or application.

In summary, a 401 Unauthorized is an HTTP status code that indicates the client's request lacks valid authentication credentials. It means that the user does not have permission to access the requested resource or perform the desired action. The server responds with this error message as a way to inform the client that they need to provide valid credentials in order to gain authorized access.

This website uses cookies to ensure you get the best experience. By using this website, you acknowledge that you understand and agree to our Privacy Policy and Terms and Conditions.