HTTP codes describe the status of a URL when a visitor attempts to access it, and include error messages that describe the problems that the visitors encountered. The codes are three-digit numbers.
There are five classes of HTTP codes, which are divided into categories by the first digit.
A first digit of 1, 2, or 3 represents a fully functional request.
A first digit of 4 represents a client-side error. The most common codes span 400 to 404.
A first digit of 5 represents a server-side error. Common codes span 500 to 510.
For more information, read the Wikipedia article on HTTP codes.
These errors are technically the result of a problem with the client’s (for example, the browser’s) request, but they often point to a problem on a website. For example, if a faulty link is on your home page, and visitors click it, they will see a 404 error.
For this reason, it is important that you monitor these errors and investigate their causes. Because these are also among the highest-profile codes (visitors see them the most), you may want to customize these error pages in cPanel’s Error Pages interface (Home >> Advanced >> Error Pages).
400 Bad Request
The user’s request contains an incorrect syntax.
The requested file requires authentication (a username and password).
The server will not allow the visitor to access the requested file. If a visitor sees this code in error, check the file’s permission settings. You can also check to see whether the file is protected in cPanel’s Index Manager interface (Home >> Advanced >> Index Manager).
404 Not Found
The server could not find the file that the visitor requested. This error commonly occurs when a visitor mistypes a URL.
These errors occur when a server cannot fulfill an apparently valid request from a visitor. Often, you will need the help of a server administrator in order to investigate these errors.
It is also important to consider that many times, a chain of servers handles an HTTP request. This means that your web server may not be the server that returned the error.
500 Internal Server Error
This error signifies that the server encountered an unexpected condition. It is a multipurpose error that displays when the server cannot gather any specific information about the problem. This error often occurs when the server cannot fulfill an application request because the application was misconfigured.
501 Not Implemented
This error signifies that the server does not support the HTTP method that the client used. This error occurs often if the server is out of date. This error is very rare and generally requires that the system administrator update the web server.
502 Bad Gateway
This error usually occurs due to improperly configured proxy servers. However, the problem may also arise when there is poor IP communication between backend computers, when the client’s ISP is overloaded, or when a firewall functions improperly.
The first step to resolve the issue is to clear the client’s cache. This action should result in the use of a different proxy to resolve the web server’s content.
503 Service Unavailable
This error occurs when the server cannot handle requests because of a temporary overload or because the server is temporarily closed for maintenance. The error signifies that the server will only be unavailable temporarily. It is possible to receive other errors in place of 503.
Contact the server administrator if this problem persists.
504 Gateway Timeout
This error occurs when a server does not receive a timely response from another server. Slow communication between upstream servers causes this problem.
To resolve this issue, contact the system administrator.
505 HTTP Version Not Supported
This error occurs when the server refuses to support the HTTP protocol that the client computer specifies. It occur if the client computer does not specify the protocol properly (for example, if it specifies an invalid version number).
This error should not occur if you have a current installation of cPanel & WHM.
506 Variant Also Negotiates
This error indicates that the server is not properly configured. Contact the system administrator to resolve this issue.
507 Insufficient Storage
This code indicates that the server is out of free memory. This error is likely to occur when a requested application cannot allocate the necessary system resources in order to run.
To resolve the issue, the system administrator must restart the server, or take steps to free or add disk space. Contact the system administrator for more information about this error message.
509 Bandwidth Limit Exceeded
This error occurs when you reach the bandwidth limit that the system administrator imposed. The only solution for this issue is to wait until the limit is reset in the following cycle.
Consult the system administrator for information about how to acquire more bandwidth.
510 Not Extended
This error occurs when the web server does not support an extension that is attached to the HTTP request.
To resolve the issue, you may need to update the server. Consult the system administrator for more information.