HTTP codes describe the status of a URL when a visitor attempts to access it. HTTP codes include error messages that describe the problems that visitors encounter. The codes are three-digit numbers.

Five classes of HTTP codes, divided into categories by the first digit, exist:

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. The most common codes span 500 to 510.

4xx Errors

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 exists on your home page, and visitors click it, they receive a 404 error.

For this reason, we strongly suggest that you monitor these errors and investigate their causes. Because visitors see these errors the most often, we suggest that you 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.

401 Unauthorized

The requested file requires authentication (a username and password).

403 Forbidden

The server will not allow the visitor to access the requested file. If a visitor receives this code in error, check the file's permission settings. You can also confirm whether the system protects the file in cPanel's Index Manager interface (Home >> Advanced >> Index Manager).

404 Not Found

The server did not find a visitor's requested file. This error commonly occurs when a visitor mistypes a URL.

5xx Errors

These errors occur when a server cannot fulfill an apparently-valid request from a visitor. To resolve these issues, contact your system administrator.

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

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 of a misconfigured application.To resolve this issue, contact your system administrator.

501 Not Implemented

That the server does not support the client's chosen HTTP method. This error occurs often if the server is out of date.

Note:his error rarely occurs. To resolve this issue, contact your system administrator.

502 Bad Gateway

This error usually occurs due to improperly configured proxy servers. However, the error also arises when there is poor IP communication between backend computers, when the client’s Internet Service Provider (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 results in the use of a different proxy to resolve the web server’s content.

503 Service Unavailable

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.To resolve this issue, contact your system administrator.

504 Gateway Timeout

A server did not receive a timely response from another server. Slow communication between upstream servers causes this error.To resolve this issue, contact your system administrator.

505 HTTP Version Not Supported

The server refuses to support the HTTP protocol that the client computer specifies. This error occurs if the client computer does not correctly specify the protocol (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

The server is not properly configured. To resolve this issue, contact your system administrator.

507 Insufficient Storage

The server is out of free memory. This error usually occurs when a requested application cannot allocate the necessary system resources in order to run.To resolve this issue, contact your system administrator.

509 Bandwidth Limit Exceeded

Your server reached the bandwidth limit that the system administrator imposed. The only solution for this issue is to wait until the limit resets in the following cycle.To resolve this issue, contact your system administrator.

510 Not Extended

The web server does not support an extension that is attached to the HTTP request.To resolve this issue, contact your system administrator.