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Error 401 And How It Is Different From Error 403

Posted in General   LAST UPDATED: MARCH 27, 2023

    HTTP 401 error and difference from HTTP 403 error

    Error 403(Forbidden) and Error 401 (Unauthorized) are almost like identical twins, but what do you think is the exact difference between the two?

    If you own or create websites, you may have come across HTTP error numbers 401 and 403. When a person tries to access a limited website or resource, this error occurs. While they may appear to be the same, there are significant variations between the two error numbers. In the following article, we'll go over the distinctions between error 401 and error 403, as well as their meaning and causes.

    RFC Standards

    Error 401

    The RFC Standard defining Error 401 (Unauthorized) is RFC7235 which says that the code conveys the message indicating the canceled request because of lacking authentication credentials for the target resource… You could then try to repeat the request with a new or replaced Authorization header field.

    But, the RFC standard that defines Error 403 (Forbidden) is RFC 7231 and it states that the server has successfully understood the request but has refused to authorize it. The authorization credentials that were provided in the request are insufficient for the server to provide access.

    Main Causes Of The Errors

    So now we know, that Error 403 happens when the user has logged in but they do not have the permission required to access the requested resource. For instance, you could be logging in to access the admin route when you only have permission for the generic user route.

    On the other hand, you will mostly encounter a 401 error when you have provided the wrong password or you have not logged in at all.

    These, we can say, are the most common causes for Errors 401 and 403.

    Some Obscure Causes

    Http 401 error causes

    There are a few occasions when the cause for the error might not be that straightforward.

    There can be occasions when the error 403 is not entirely dependent on the logged-in user’s credentials.

    For instance, there could be a server that has locked down its resources such that it only allows access from a fixed range of IP addresses. The VPN could be potentially circumvented with the latter.

    On the other hand, even if you have entered the correct credentials, the 401 error could occur. But, it has to be admitted that this could only be encountered while developing authenticated back ends of your own. But a malformed authorisation header will again return a 401.

    For instance, you might want to include in the request a JWT (JSON Web Token), if you have it. A JWT expects the format Authorization: Bearer eyJhbGci......yJV_adQssw5c.

    You could encounter the 401 error if you forget to use the word “Bearer’ before the JWT.


    Understanding the membership and identity operators in Python is essential for writing efficient and concise code. By using these operators, you can easily check for the presence or absence of values in a sequence, or compare the identity of two objects. Similarly, understanding the differences between error 401 and error 403 is crucial for website owners and developers to troubleshoot issues related to restricted access. By applying the knowledge gained from this article, you'll be better equipped to handle these common scenarios and write more robust Python code.

    Frequently Asked Questions

    1: What is a 401 error in HTTP?

    A 401 error in HTTP is an "Unauthorized" error code that occurs when a client attempts to access a resource without proper authentication or authorisation credentials.

    2: What is a 403 error in HTTP?

    A 403 error in HTTP is a "Forbidden" error code that occurs when a client attempts to access a resource that they do not have permission to access, even with proper authentication credentials.

    3: How are 401 and 403 errors different?

    401 errors occur when a client is not authenticated or authorised to access a resource. 403 errors occur when a client is authenticated but does not have permission to access a resource.

    4: What can cause a 401 error?

    A 401 error can be caused by various factors, such as entering incorrect login credentials, missing or expired authentication tokens, or attempting to access a protected resource without proper authorisation.

    About the author:
    Expert technical writer who simplifies complex technological concepts for lay audiences. Focused on providing insightful analysis and entertaining listicles on a wide variety of topics in the technology sector.