401 Unauthorized Error: What It Is & 7 Methods to Fix It

Experienced E-commerce Agency for Magento/ Adobe Commerce/ Shopify/ Shopware Development

In web communication, the HTTP status codes are important as they give information about request outcomes. One of the significant error codes is the 401 Unauthorized error. This error occurs when authentication credentials are missing or invalid, indicating that access is denied. Understanding and resolving the errors promptly is vital to maintain secure and seamless web services.

Table of Contents

What Are 401 Unauthorized Errors?

401 Unauthorized errors are HTTP status codes that indicate a lack of valid authentication credentials. If a client tries to access a resource that needs authentication but fails to give the proper certifications or gives incorrect ones, the server will respond with a 401 Unauthorized error. This error serves as a prompt for the client to provide appropriate authentication before being granted access.

401 Unauthorized Errors meaning

Differentiating this error from other HTTP status codes is essential. While 403 Forbidden signifies an explicit denial of access and 404 Not Found indicates that the requested resource does not exist, 401 Unauthorized highlights explicitly the absence of valid authentication credentials.

Typical scenarios where the error occur include accessing protected web pages, APIs, or restricted areas that require authentication. These errors can also arise when using expired or revoked authentication tokens, attempting access with insufficient privileges, or encountering misconfigured authentication mechanisms. It is crucial to address these errors promptly to ensure secure and seamless web operations.

7 Causes of 401 Unauthorized Errors

Encountering this error can discomfit users and website administrators. Understanding the causes behind this error is essential in order to diagnose and resolve the issue effectively. Let’s explore seven potential causes that may lead to error:

Incorrect or missing authentication credentials

One of the most common causes of a 401 Unauthorized error is when users provide incorrect or incomplete authentication credentials. Whether it’s mistyped usernames, passwords, or missing authentication headers, any inaccuracy in the credentials can result in a denied access response from the server.

Inaccurate or absent authentication credentials

Expired or invalid sessions or tokens

Authentication tokens or sessions typically have an expiration time. When a user’s session or permit expires or becomes invalid due to security reasons, attempting to access protected resources will trigger a 401 Unauthorized error. By implementing this security measure, only users who have been authorized can gain access to sensitive data.

Insufficient privileges or access restrictions

Certain resources within a website or application may require specific privileges or access permissions. In case a user does not have the necessary permissions or tries to access restricted zones without proper approval, the server will issue a 401 Unauthorized error. This error serves as a safeguard against unauthorized access to sensitive information or functionalities.

Incorrect URL or endpoint

Sometimes, users mistakenly enter an incorrect URL or endpoint when accessing a website or API. In such cases, the server may not recognize the requested resource and respond with a 401 Unauthorized error. Double-checking the URL or endpoint can help ensure that the right resource is being accessed.

Verify URL or endpoint for correct resource access

Misconfigured authentication mechanisms

Improper configuration of authentication mechanisms on the server side can also lead to error. This can include disabled or misconfigured authentication protocols, mismatched certificates, or improperly implemented security measures. It is crucial to review and adjust authentication mechanisms to prevent such errors.

Blocked IP addresses or firewalls

Sometimes, the server may block specific IP addresses or have firewall restrictions to protect against unauthorized access or malicious activities. If a user’s IP address is blocked or restricted by the server or there are firewall rules preventing access, a 401 Unauthorized error will be triggered when attempting to access the protected resources.

Cross-Origin resource sharing (CORS) restrictions

When making cross-origin requests, it’s essential to consider Cross-Origin Resource Sharing (CORS) policies. If the server does not have appropriate CORS policies configured, it may reject the request and respond with a 401 Unauthorized error. CORS restrictions are in place to protect against unauthorized access to resources from different domains or origins.

By understanding these potential causes of the error, website administrators and developers can effectively troubleshoot and resolve the issues.

Properly validating and managing authentication credentials, ensuring valid sessions or tokens, granting appropriate access privileges, and correctly configuring authentication mechanisms can help mitigate 401 Unauthorized errors, providing users with secure and seamless experiences.

7 Troubleshooting Steps for Resolving 401 Unauthorized Errors

Verify authentication credentials

Start by double-checking the authentication credentials provided by the user. This includes usernames, passwords, or any authentication headers required for accessing the resource.

Confirm the legitimacy of the provided authentication information

Ensure the certificates are accurate, properly formatted, and match the expected authentication requirements. Correct any errors or missing information to ensure successful authentication.

Refresh sessions or tokens

Sometimes, a user’s session may expire, or their authentication token invalidates. This can cause a 401 Unauthorized error when they try to access a protected resource.

To fix this, refresh the session or generate a new authentication token. This may involve extending the session duration or issuing a unique token to authorize the user’s access.

Check access privileges

Another possible cause of the error is when a user does not have the necessary privileges or permissions to access the requested resource. For example, they may be trying to access an admin-only area or a restricted feature.

Confirm if the user has permission to access certain resources

To resolve this, you need to review the user’s access privileges and permissions and make sure they are appropriate for the resource they are trying to access. If not, you need to grant them the proper access rights or modify their permissions accordingly.

Correct URL or endpoint

A simple typo in the URL or endpoint can also lead to a 401 Unauthorized error. For instance, the user may have entered an extra character or missed a slash in the URL. This can result in the server not recognizing the requested resource and rejecting the request.

To avoid this, you need to carefully verify the URL or endpoint and compare it with the expected resource location. If there are any discrepancies, correct them and make sure you are accessing the right resource at the right endpoint.

Configure authentication mechanisms

Occasionally, the problem may lie in the server-side authentication mechanisms. They may be misconfigured or disabled, resulting in authentication failures and 401 Unauthorized errors.

To fix this, you need to check the server-side authentication mechanisms and make sure they are correctly configured. This includes enabling the necessary authentication protocols, verifying the validity of certificates or keys, and adequately configuring authentication components.

If there are any misconfigurations, address them and ensure successful authentication.

Unblock IP addresses or firewalls

In some cases, a user’s IP address may be blocked by the server, or there may be firewall restrictions that prevent access to the desired resource.

This can happen when the server detects suspicious or malicious activities from specific IP addresses or when there are firewall rules that limit access to specific resources.

To resolve this, you need to identify the IP address blocking or firewall rules causing the issue and take appropriate action to unblock the IP address or adjust the firewall settings. By doing so, you can allow authorized access to the resources and resolve the error.

Enable cross-origin resource sharing (CORS) policies

For cross-origin requests, you need to consider Cross-Origin Resource Sharing (CORS) policies. These policies allow requests from different origins or domains to access resources on your server.

If your server does not have proper CORS policies in place, it may reject bids from various sources, leading to a 401 Unauthorized error.

To avoid this, you must enable the necessary headers and policies to allow requests from specified origins and avoid authentication issues.

7 Methods to Prevent 401 Unauthorized Errors

7 ways to control 401 Unauthorized Errors

Working together to eliminate any 401 Unauthorized errors on your website or app is absolutely crucial for ensuring a secure and seamless user experience. To maintain a reliable authentication system, it is vital to adhere to these 7 best practices to avoid errors.

  • Implement strong authentication mechanisms: Utilize secure and robust authentication protocols, such as OAuth or JWT, to protect user credentials and ensure secure authentication. Consider implementing multi-factor authentication for an additional layer of security.

  • Use secure transport layer: Always transmit authentication data over encrypted channels, preferably HTTPS, to prevent unauthorized interception and protect sensitive information.

  • Employ proper error handling: Implement appropriate mechanisms to provide clear and informative error messages when authentication fails. This helps users understand the issue and take necessary actions, reducing confusion and frustration.

  • Regularly update access controls: Periodically review and update access controls to align with user roles and responsibilities. Remove unnecessary privileges and ensure access is granted based on the principle of least privilege.

  • Implement token expiration and renewal: Set reasonable expiration periods for authentication tokens and sessions. Implement mechanisms to automatically renew or refresh tokens before expiration, minimizing the risk of users encountering errors due to expired tokens.

  • Perform thorough testing: Conduct comprehensive testing to identify and fix potential authentication issues. Perform functional and security testing to ensure the authentication system works correctly and securely.

  • Educate users on security best practices: Educate your users on essential security practices, such as creating strong passwords, avoiding sharing their credentials, and being cautious of phishing attempts. Encourage them to stay vigilant and report any suspicious activities.

Common Error: “The request failed with HTTP status 401 Unauthorized”

There is a common error called “The request failed with HTTP status 401 Unauthorized”

The error message indicates that the request to access a particular resource or page was unsuccessful due to unauthorized access. This means that the user or client making the request lacks the necessary authentication credentials to gain access to the requested resource. To troubleshoot and resolve the “401 Unauthorized” error, follow these steps:

  • 1. Verify authentication credentials: Check if the provided username, password, API key, or other certifications are correct. Typos or incorrect credentials can lead to authorization failures.

  • 2.Refresh authentication tokens or sessions: If using tokens or sessions for authentication, refresh or regenerate them to ensure they are valid and not expired. This step is significant if the error occurs after inactivity.

  • 3. Confirm access rights and privileges: Confirm that the user or client has the necessary access rights and privileges to access the requested resource. Check if any changes have been made to access control lists or permissions that could have caused the error.

  • 4. Review authentication mechanisms: Inspect the authentication mechanisms, such as OAuth, JWT, or other authentication protocols. Verify that they are correctly configured and functioning as intended. Misconfigurations or blocked mechanisms can result in authorization failures.


In conclusion, we have explored the concept and causes of 401 Unauthorized errors, along with troubleshooting steps and prevention methods.

Remember, understanding and addressing 401 Unauthorized errors is critical to maintaining a secure and reliable online presence. Stay vigilant, follow best practices, and prioritize authentication and access control to ensure a seamless and trustworthy digital environment.

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Vinh Jacker
Hello, I'm the Chief Technology Officer of Mageplaza, and I am thrilled to share my story with you. My deep love and passion for technology have fueled my journey as a professional coder and an ultra-marathon runner. Over the past decade, I have accumulated extensive experience and honed my expertise in PHP development.
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