Computer crash Image Credit: Getty Images/Hemera

Have you ever been surfing the net or working on your computer only to be confronted by an error message featuring a number that makes literally no sense to you at all? It’s very likely that you have, but what does it all mean?

Error codes are three digits long. If they start with a “1” (1XX) then they are for your information. If they start with a “2” (2XX) then they are indicating a successful connection attempt. An error number beginning with “3” (3XX) means “redirection” – that you must do something else before you can do what you set out to.

An error number beginning with “4” (4XX) means “Client Error”. This basically means there is a problem with your computer, rather than the server belonging to someone else.

Finally, an error number beginning with “5” (5XX) means that there is a server error, and that the website you are currently trying to access is being affected by an internal server issue.

There are indeed quite a few error messages out there, and knowing what they mean may make it easier for you to try and fix the issue. Failing that, by telling your IT administrator what the number was will make it easier for them to trace the problem.

Here are some of the most common error numbers:


100         Continue            

101         Switching protocols, or procedures         


200         Action completed successfully

201         Success! Request has been created following a POST command

202         Your request has been accepted for processing, but the processing isn’t finished

203         Computer only has partial information it needs to run

204         The server has received your request but there is no information to send back

205         Content has been reset               

206         Your requested file was partially sent because the web page likely crashed or refreshed


300         There are multiple choices available       

301         File has been moved permanently. Directory requested instead of specific file. You will notice that index.html, index.htm, home.html, or home.htm has been added to the

302         Moved temporarily        

304         The cached (hidden) version of the requested file is the same as the file to be sent, it’s not updated

305         A substitute file has been used (proxy)

Client error

400         Bad request! The server doesn’t understand. Clearing the cache should help.

401         Unauthorised access. You don’t have the correct access rights, user name or password

402         Payment is required for access 

403         Forbidden! The file does not have permission that allows the pages to be viewed on the web

404         Not found. For whatever reason, the web page is not available. This could be that you’ve entered the wrong web address     

Server error

500         Server error. Usually caused by a server that has not been configured properly

501         Not implemented

502         Bad gateway. This means that the server you're contacting is a gateway or proxy (substitute) server. It is not receiving a valid response from the main server that should actually be dealing with the request

503         Out of resources. This means that the system is overloaded

504         Gateway timed-out. A slow internet connection can be caused by multiple things, such as defective Ethernet cables, old switches, or general poor service. It could also mean the server is in need of maintenance

505         HTTP version is not supported