Server Error Codes
‘HTTP Error 404 – File or directory not found’… sounds familiar? This is a common error that we often confront while searching for a specific webpage on the Internet. In this era of Internet technology digital communication and sharing information are taking place through web server. Digital information, in the form of web pages, is stored in the web server and is accessible by us through TCP/IP (Transmission Control Protocol/ Internet Protocol).
Server errors happen at the time of processing the request of a client. Let us simplify the feature. Since websites are stored in web server therefore, to access a particular site we need to send a request through a browser, e.g., Internet Explorer, Netscape, Mozila etc.
In general, we type the request i.e., URL (Uniform Resource Locator - the standardized pointer format to access information from the World Wide Web) of the website, in the address bar of the browser and click on the corresponding ‘Go’ button. The request is then transferred from the local computer to web server through the Internet. Web server will then process the given request and display the copy of the requested webpage in our local computer. Processing the request is considered as the primary task of web server.
Apart from redirecting the copy of requested webpage to client’s desktop/laptop, web server also detects errors. These errors are commonly known as ‘Server Errors’ and are displayed on the screen with error code and error message.
Error can be triggered either from the Web Server or due to any mistake of the client. In the absence of Internet connection you will find error from the Client Server. On the other hand, Web Server detects errors if the server is incapable of processing or understanding the request.
Categorizations of Server Errors
We can classify the server errors in two major parts – Connection Error and Web Server Response Codes and Messages.
Connection Errors are triggered when our request failed to connect and process in the web server. An error code is displayed if and only if a request from local computer is connected with the server. Since connection error occurs in the absence or failure of proper connection of the request between local computer and server, therefore you will never find any error code, only error message will be displayed.
Response Code and Message will generate when a request is connected and processed in the web server. You will find web server response code (commonly known as error code) and the message if the server detects any error during the time of processing your request. This ‘Response Code’ is also known as ‘Status Code’ and is identified by a three-digit integer accompanied by textual information. This textual information is known as response message. Response code, which is less than ‘400’, is not considered as ‘Error’. Response code, which is equal to or greater than ‘400’, is displayed on the screen if there exist any error in the webpage.
Client Error Code and Server Error Code
Web server error codes can be of two types – Client Error Codes and Server Error Codes. Three digit error codes, which start with ’4 ‘and ’5’, are considered as Client Error Code and Server Error Code, respectively. Client error code is displayed if the syntax of the request is not valid. In this case, the server will fail to process the request and display Client Error Code. However, you may get error code by sending a valid request with right syntax. If it is a problem of that particular server then you will get the Server Error Code that starts with ‘5’.
Client Error Code
Three digit server error codes, which start with the digit ‘4’, are known as Client Error Codes. Following are some common client error codes:
Error Code: 400
This error code is displayed if the client (general user) makes any bad request with malformed syntax. If you find such error code on the screen then thoroughly check the syntax of the request in the address bar of the browser and make necessary changes.
Error Code: 401
You will find this error if there is any mismatch in the IP address of the online application that is managed through a server. If the user is not authorized to access the database of an online application, the host server will restrict the access of the client. Perfect IP address, Username and Password are the fields, which are used for online applications, to check the authorization of the users.
Error Code: 404
This server error code appears on the screen if the requested URL does not exist in the server. However, web servers can detect the availability or the forwarding address of the requested URL through the internal mechanism. You remove a file temporarily from the server then people will get the error code 410 instead of 404.
Error Code: 406
If there is a mismatch between the request header and the format of the digital document then you will get this error on your browser window. Any request will be carried to the hosting server through a client side server. For example, if file types, languages and encoding features are not properly specified in the client side server then you may get this error code if there exist disparity in the specifications. In other word, it can be said that if a server identifies that the requested data is not acceptable to the client then that server will return a header with the error code 406.
Error Code: 407
The feature of this error code is quite similar to code 401. This server error is displayed for online application where a client needs to authenticate himself/herself in a proxy server. If the setup of the application does not authenticates the browser in place of the proxy server then it will restrict the client to access the data as well as display the error code 407.
Error Code: 412
If a web server considers that the HTTP (Hyper Text Transfer Protocol) request sent by the client contains precondition, which are not fulfilled then you will find the error code 412. You will find this error if your client system acts as a web browser. If you encounter such error code it is recommended to contact with your Internet Service Provider.
Error Code: 414
In general the length of the URL are specified in the browser. If you enter large data stream (with more than 5000 characters) the server will fail to process your request and display the error code 414. You need to reconfigure the server to view the requested page that has long stream of characters.
Error Code: 415
You will find this error code on the browser window if the server does not allow the media type of the requested URL by the client. However, you will find this error if the streaming media type in the server does not match with the media type of the URL, which is specified in the request. Error code 415 will also appear if the media type of the requested URL is incompatible with Hyper Text Transfer Protocol method that is specified on the request.
Server Error Code
Three digit server error codes, which start with the digit ‘5’, are known as Server Error Codes. You will encounter server errors when a server is incapable of processing a valid request sent by the client. Following are some common client error codes:
Error Code: 500
Error code is not the outcome of any error in client side. The error is generated if the web server fails to process the valid request of a client. This is considered as an unexpected condition, where the server itself is not specific about the errors. During this process, web server will record the errors in an internal log. Therefore, it is recommended to analyze the server logs to identify the actual error.
Error Code: 501
You will find this error when the web server does not allow the required functionality of the request sent by a client. The methods of HTTP protocol are – Options, Get, Head, Post, Put, Delete, Trace and Connect. Error Code 501 will appear if the method declared in the requested HTTP data stream does not match with the specified set of eight methods. However, it is observed that old web server does not support valid methods and as a result a client may encounter the error code 501.
Error Code: 502
Often you will find a gateway or proxy server between the client and an upstream server. Any request triggered by the client will reach to the upstream server through a proxy server. This error will appear on the browser window when the protocol for exchanging digital information varies between upstream server and a gateway or proxy server.
Error Code: 503
If a web server is overloaded or closed temporarily due to maintenance job then that server will not process any request sent by the client and will display the error code 503. This will stay for a short period of time. This error implies that complete service of the web server is not available temporarily and will start working after the maintenance job.
Error Code: 504
This is another error that you may get if there is any proxy server between the client and upstream server. Proxy server carries the request that is sent by a client to the upstream server and following the same path it redirects the response from upstream server to the client. If the proxy server fails to get timely response from he upstream server then it will display the error code 504 on the browser window.
Error Code: 505
The HTTP protocol version matters for receiving the right response from the web server. If the HTTP version (e.g., 1.1) of a request does not match with the existing HTTP version (e.g., 0.9) of a server then the server will fail to process the valid request and display the error code 505 on the browser window.
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