Every error page we see on the web has an HTTP status code sent by web server. The first digit marks the class of the status code.
- 1 XX status code have informational purpose.
- 2 XX status code indicates success
- 3 XX status code indicates redirection
- 4 XX status code indicates client side errors
- 5 XX status code indicates server side errors
Client Side Errors
1. 400 – Bad Request
Whenever the client sends a request the server is unable to understand the 400 Bad Request error page.
There is something unstable on the client side.
2. 401 Authorization Required
When there is a password protected web page behind the client’s request, the server responds with 401 Authorization Required Code. It popup once and ask user to provide a login password.
3. 403 Forbidden
When the server understands the client’s request clearly but for some reasons refuses to fulfil it. It can be useful to harden the site against being hacked by hiding the directory structure or files that contains unprotected information.
4. 404 Not found
It is the most well known HTTP status code. When ever the server doesn’t find anything on the requested location.Either the visitor may mistyped or permalink structure of site has been changed. When a site has recently moved to another web server and DNS still points to old location. This type of problem usually disappears after a short time.
5. 408 Request Time out
When the request of the client takes too long the server times out, it closes the connection and the browser displays a 408 request time out error message.
Server Side Errors
1. 500 Internal Server Error
It is used whenever the server encounters an unexpected condition that prevents it from fulfilling the client’s request. The 500 error code is generic one, it is returned when no other server side error codes makes any sense.
2. 502 Bad gateway
It represent a communication problem between two servers. It occurs when the client connects to a server acting as a gateway that needs to access an upstream server that provides additional service to it.
3. 503 Service Temporarily Unavailable
A temporary condition that will be resolved after some delay. The 503 error code means that the web server is currently not available.