You’ve encountered the dreaded 401 Unauthorized error and cannot access necessary information, which is why you’re here. Perhaps the problem is a grumpy server that is refusing to recognize you, an expired session, or a login issue.
Whatever the cause, one thing is certain: it’s annoying that you’re locked out.
When websites or APIs require authentication but don’t receive it in the desired format, this error occurs more frequently than you might imagine. The good news? It is correctable.
This blog will provide you with step-by-step instructions on how to resolve the 401 error, regardless of whether you’re a developer troubleshooting an API request or a casual internet user. Now let’s get to work.
What is a 401 Unauthorized Error?
An HTTP response status code 401 Unauthorized denotes a problem with authentication. A 401 error is returned by the server when a client requests access to a resource without providing legitimate authentication credentials.
In most situations, this error occurs when:
- Credentials for authentication are either missing or inaccurate.
- The user’s session is no longer active.
- The security settings of the website limit access.
- API authentication fails because the tokens are invalid or expired.
In contrast to a 403 Forbidden error, which happens when authentication is successful but the user lacks the required authorization to access the resource, a 401 unauthorized error is different.
Common Causes of a 401 Unauthorized Error
Several factors can lead to 401 unauthorized error. Among the most frequent reasons are:
1. Inaccurate login information
The password or username that was entered is not correct.
The previous credentials are no longer valid due to recent changes.
Additional verification is necessary because multi-factor authentication (MFA) is enabled.
2. Session tokens that are invalid or expired
After a certain amount of inactivity, some websites automatically log users out.
The server might ask the user to log in again if an authentication session ends.
3. Inaccurate or missing tokens for API authentication
A 401 error may occur during an API interaction if there are missing or incorrect API keys or tokens.
Authentication issues may also arise from expired OAuth tokens.
4. Restrictions on security or firewalls
Because of security concerns, some websites prevent access from specific IP addresses.
A firewall-protected website might deny requests from unidentified sources.
5. Problems with Cookies and Caches
Access denial may result from out-of-date cached authentication data.
Authentication may not function properly due to corrupted cookies.
6. Website Administrator-Restricted Access
The owner of the website might only be able to access specific users or areas.
Certain content might need paid subscriptions or extra permissions.
How to Fix a 401 Unauthorized Error?
To fix a 401 Unauthorized error, follow these troubleshooting steps:
1. Confirm your login information
- Make sure you’re using the right username and password.
- Update your credentials if they have changed recently.
- If needed, reset the password.
2. Empty the Cookies and Cache
Authentication problems may arise from outdated cookies and cache.
In Chrome:
- Navigate to Settings > Security & Privacy > Empty browsing history.
- Choose cookies, other site information, and cached files and images.
- Select “Clear Data.”
- Try again after restarting the browser.
3. Log out and then back in
- Session tokens can be refreshed by logging out and re-authenticating.
- Try access again after closing the browser and logging in again.
4. Verify the URL
- Make sure you enter the URL correctly.
- Certain websites require precise spelling on their secure login pages.
5. Clear the DNS cache
Clearing the DNS cache could fix the issue if it contains out-of-date authentication information.
- Windows: Type ipconfig /flushdns into the Command Prompt.
- Mac: Type sudo killall -HUP mDNSResponder into the Terminal window.
- Try to gain access again after restarting the browser.
6. Turn off browser add-ons
- Extensions of security may obstruct authentication.
- Try visiting the website again after disabling extensions.
7. Go into Incognito Mode
- To avoid using the cache and stored cookies, open a private browser window.
- The problem should be fixed if the website functions in incognito mode after clearing the cache and cookies.
8. Verify the security and firewall settings
- Access to particular websites is blocked by certain firewalls.
- Try visiting the website from a different network or, if required, modify the firewall settings.
9. Get in touch with the website administrator
- Get in touch with customer service or the site administrator if access is restricted.
- Check if any particular permissions are required.
10. Check the Authentication Tokens for APIs (For Developers)
- Make sure the tokens and keys for the API are set up correctly.
- If you’re using OAuth, make sure the token is valid and update any expired tokens.
HTTP Authentication Methods and 401 Errors
Different authentication techniques are used by websites and APIs to confirm user identity. When these techniques don’t work, a 401 Unauthorized error frequently happens. Typical techniques for authentication include:
A username and password must be sent in the request header for basic authentication. If it’s wrong, a 401 error is raised by the server, denying access.
Bearer Token Authentication
This authentication method uses a token (like JWT) in the request header. A 401 error is caused by an invalid or expired token.
OAuth Authentication
A safe technique that uses permission from a third party (such as a Facebook or Google login). If the access token is revoked or expires, a 401 error may appear.
Authentication of API Keys
A valid API key is frequently required by APIs. A 401 unauthorized error may be caused by an outdated, inaccurate, or missing API key.
Troubleshooting the error is made easier when one is aware of the authentication method being used.
401 Error Variations Across Browsers & Platforms
Depending on the platform, application, and browser, a 401 error may show up differently. This is how the error could appear on various platforms:
1. Web browsers (Flash, Edge, Safari, Chrome):
On a blank page, the message “401 Unauthorized” or “Access Denied” appears.
Some websites that require authentication send users to a login page.
2. Mobile applications (Android, iOS):
Applications that use API requests may display a generic “Session Expired” or “Authentication Failed” message.
Certain applications ask users to enter their login information again in the event of a 401 error.
3. API Clients (Postman, cURL):
The response code 401 appears in API responses along with a message such as {“error”: “Unauthorized” or “message”: “Invalid API key”}.
API headers can be examined by developers to look for inaccurate or missing authentication information.
Recognizing the error’s appearance across various platforms can assist in identifying and fixing the issue faster.
Difference Between 401 and Other Authentication-Related Errors
Troubleshooting can be aided by knowing how a 401 Unauthorized error varies from related HTTP errors:
1. 401 Unauthorized (authentication was needed, but it wasn’t successful)
The server needs to be authenticated, but no legitimate credentials were sent.
usually resolved by reloading authentication tokens, entering the correct API key, or logging in.
2. 403 Prohibited (Verified, But Without Authorization)
Although the user is recognized by the server, access is denied because of inadequate permissions.
For instance, attempting to access an admin page without the necessary permissions.
3. 404 Not Found (No Resource Found)
The server does not have the requested page or resource.
Unrelated to authentication; typically the result of a typographical error in the URL.
4. 500 Internal Server Error (Problem on the Server Side)
A general server error is frequently brought on by crashes or incorrect configurations.
This is a server-side issue rather than an authentication issue, in contrast to 401.
The correct troubleshooting actions can be taken by developers and users by differentiating between these errors.
Preventing 401 Errors in the Future
Use these best practices to reduce the likelihood that you will experience a 401 unauthorized error in the future:
- To make sure your login information is correct, use a password manager.
- If you work with APIs, update your tokens regularly.
- To improve security, turn on two-factor authentication (2FA).
- To prevent typing incorrect URLs, bookmark login pages.
To avoid outdated authentication problems, periodically clear your cache and cookies.
NO ERRORS ANYMORE!
Incorrect or missing authentication credentials result in a 401 unauthorized error. Verifying login credentials, cleaning out cache and cookies, examining firewall settings, and updating authentication tokens are usually necessary to fix the issue.
Users and developers can effectively identify and fix authentication problems by using the troubleshooting procedures described in this guide, guaranteeing continuous access to websites and APIs.
It is advised to get in touch with the website administrator or support staff for persistent problems.
FAQ’s
It indicates a failure in authentication, preventing access to a resource.
A 401 error means authentication is required but missing or incorrect, while a 403 error means authentication is valid but access is denied.
Incorrect login credentials, expired sessions, missing API tokens, firewall restrictions, and cache issues.
Check login details, clear cache and cookies, log out and back in, verify the URL, and disable security extensions if needed.
Yes, expired authentication sessions can trigger a 401 error, requiring a new login.
Yes, ensure API tokens are valid, refresh expired OAuth tokens, and confirm correct authentication headers.
