HTTP 401 Unauthorized — What It Means and How to Fix It

Common Causes

• Missing or incorrect 'Authorization' header in the request.
• Expired authentication token (e.g., JWT, session cookie).
• Invalid username or password provided.
• Attempting to access a resource that requires authentication without logging in.
• Server-side misconfiguration of authentication mechanisms.

Code Examples to Handle HTTP 401

curl -I https://httpbin.org/status/401

fetch('https://httpbin.org/status/401')
  .then(response => {
    if (response.status === 401) {
      console.log('Handled Unauthorized');
    }
  });

import requests

response = requests.get('https://httpbin.org/status/401')
if response.status_code == 401:
    print("Received Unauthorized")

How to Fix It

1. Verify that an 'Authorization' header is present in your request and contains valid credentials (e.g., Bearer token, Basic Auth).
2. Check the validity and expiration of your authentication token or session. If expired, obtain a new one.
3. Ensure the username and password (if using Basic Auth) are correct and match the server's expected credentials.
4. If using a client library or framework, confirm that it's correctly handling authentication and attaching credentials to requests.
5. On the server-side, review your authentication middleware or logic to ensure it's correctly validating credentials and returning the appropriate 401 response.

Related Status Codes