HTTP or HTTPS status codes are issued by a server when a client makes a request to the server when you visit a website. The hosting server sends the codes to the requesting device. These codes let the requesting device know how to handle the connection. Essentially, the hosting server tells the requesting device how to handle the request and what to do next.
There are five standard classes of status codes:
- 1XX informational response (request received) - no errors
- 2XX successful request (request understood and accepted) - no errors
- 3XX redirection (further action required to complete request) - potential error
- 4XX client error (request cannot be completed) - definite error
- 5XX server error (server failed to fill valid request) - definite error
In this article, we’ll discuss some of the most common http error codes like redirect codes (3xx), client error codes (4XX), and server error codes (5XX).
3xx Redirection Codes
The status code category 3XX tells the client that they need additional measures in order to complete their request. The target might have been moved to a different location or otherwise needs to be accessed at a new source.
301 Redirect or 301 Moved Permanently
The link you are attempting to connect has been redirected and moved permanently. Future requests should connect to the new link.
The link you are attempting to connect has been temporarily redirected. Future requests should continue to use the same link. However, the original URL remains valid.
303 See Other
A separate GET request to another storage location must be sent in order for the client to receive the resource or page they are looking for.
304 Not Modified
The resource hasn't changed since the last inquiry from the client. It won't be transmitted again.
307 Temporary Redirect
The resource the client requests has availability on the webserver, but temporarily can't be found at its original URL. Similar to a 302 or 303 error, a different URL must be temporarily used. The original URL still remains valid. The browser follows the same method as used for the original request.
4xx Client Error Status Codes
The status code category 4XX tells users that there is an issue with their request, not with the server. These errors can occur for a variety of reasons, such as if the user misspells a URL or if a website has been removed. It's a disconnect between what the user is attempting to access and its availability to the user.
400 Bad Request
The server to which you are trying to connect could not understand the request. Potential causes include a malformed request syntax, an invalid request message framing, or deceptive request routing. In order to correct the error, do not repeat the request. Modify the link before making any future connections. Furthermore, check that you entered the URL correctly and that the link you clicked contains the correct URL.
The user is unauthorized to access the target resource. In other words, the request could not be authenticated. This can occur if a client fails to provide proper authentication to the server they are trying to access or if the server banned the client. To correct the error, first check the URL to ensure its accuracy. Then, flush the DNS and clear browser cookies. Log out and log back in. If none of these actions work, it could be the case that the website’s server is down. In this case, try contacting the webmaster of the website.
The server is refusing the request. The client is forbidden from completing the request. For example, the user might not have the necessary permissions or the user may be attempting a prohibited action. 403 error codes are similar to 401 codes, but with a 403 forbidden error, re-authenticating makes no difference.
If you receive a 403 error code and feel it was made by mistake, contact the webmaster of the website to request access. In rare cases, the code could be caused by an error on your end. With any error code, it’s always worth a shot to check the URL, refresh the page, and clear your cookies and cache.
404 Not Found
The requested resource could not be found. This could be temporary or permanent.
404 Page Not Found errors are one of the most common errors on the Internet. They occur when you have successfully communicated with the server, but the server cannot find what was requested. For example, a dead link can cause a 404 error. This happens often because web administrators frequently update pages without updating corresponding links elsewhere on the Internet. To correct the issue, first refresh the page. Check the URL and delete the cache and cookies. Browse the website or use a search engine to locate the page you're trying to view. You can contact the webmaster of the website if the Contact Us or Support pages are available. If the entire site is down and no pages are accessible, they may be experiencing an outage. You can try again later.
405 Method Not Allowed
The server's configuration does not allow for the specific action to be performed with a particular URL. For example, a form with a GET request that requires data to be presented via POST request may cause with error.
Another common cause of this error is simply inputting an incorrect URL. If that isn't the case, the error is likely a server issue.
417 Expectation Failed
The expectation provided in the request's Expect header could not be met. If this happens, you need to check the Expect header and make sure everything is correct.
5xx Server Error Status Codes
The status code category 5XX is the opposite of status code category 4XX; it means the error was on the server's end, not the client's. However, it still essentially stems from a disconnect between the client and the what is available to the client.
500 Internal Server Error
When an unexpected 500 error occurs and no specific reason for the error can be found, the server prevents the completion of the request. Because 500 server error codes are so generic, they are fairly difficult to troubleshoot. Additionally, since it’s a server error rather than a client error, there is likely nothing you can do to solve it.
If you receive a 500 error code, contact the website if a Contact Us page is viewable. Also, it’s always worth a shot to check the URL, refresh the page, and clear your cache.
501 Not Implemented
The server does not support the functionality required to complete the request. This response code occurs when the server does not recognize the request method. For a list of HTTP request methods and their support for each browser, visit Mozilla.org.
503 Service Unavailable
The server is unable to process the request at this time. Usually, service unavailable error codes mean the site is down for maintenance or overloaded. Typically, this is a temporary state. The best thing to do when you encounter a 503 error is to try again later.
504 Gateway Timeout
The server did not receive a timely response from the upstream server in order to complete the request. Your server, acting as a gateway, waits too long to receive a response from the upstream server and times out. This usually happens when the upstream server is down or overloaded
505 HTTP Version Not Supported
The HTTP version is not supported by the server, making it unable to communicate with the client. If you receive this error, check the URL to make sure it is correct, and make sure you are using the latest version of your browser.
For a complete list of HTTP Status Codes, please visit IANA.