This can be caused by the protocol not being specified properly by the client computer for example, if an invalid version number has been specified. This error occurs when the server refuses to support the HTTP protocol that has been specified by the client computer. To resolve this issue, contact the system administrator.
The problem is caused entirely by slow communication between upstream computers. This error occurs when a server somewhere along the chain does not receive a timely response from a server further up the chain. It is possible to receive other errors in place of 503.Ĭontact the server administrator if this problem persists. The error indicates that the server will only temporarily be down. This error occurs when the server is unable to handle requests due to a temporary overload or due to the server being temporarily closed for maintenance. This action should result in a different proxy being used to resolve the web server's content. The first step in resolving the issue is to clear the client's cache. However, the problem may also arise when there is poor IP communication between back-end computers, when the client's server is overloaded, or when a firewall is functioning improperly. This error is usually due to improperly configured proxy servers. It is a very rare error and generally requires that the web server be updated. This is most often caused by the server being out of date.
This error indicates that the HTTP method sent by the client is not supported by the server. This often occurs when an application request cannot be fulfilled due to the application being configured incorrectly on the server. This error indicates that the server has encountered an unexpected condition. It is also important to consider that quite often, a chain of servers is handling an HTTP request, so that it may not be your server that is returning the error. Often, you will need the help of a server administrator to investigate them. These errors are caused by the server being unable to fulfill an apparently valid request from a visitor. You can read about best practices for 4xx codes. With a 4xx code, typically the client or user has to fix an error before trying again, but there are some exceptions.
With a 5xx code, the request can be present with no changes and you will get the requested result when the server has been fixed.
A 5xx code means the problem was caused by the server.