HTTP status codes (4xx and 5xx) are displayed when there is some kind of error while loading a web page. You have probably all seen them. HTTP error codes can appear in all browsers, such as Internet Explorer, Firefox, Chrome, etc.
Below we will list the most common 4xx and 5xx error codes.
Note: HTTP status codes starting with 1, 2, and 3 exist but we will not mention them as you will not encounter them.
400 (Bad Request)
The HTTP status code 400 Bad Request means that the request sent to the server to open a web page was somehow malformed.
So the server cannot understand the request, could not process it, and instead of opening the page you requested, it gives the 400 error.
401 (unauthorized access)
The HTTP status code 401 Unauthorized Access means that the page you are trying to view cannot be loaded until you log in with a valid username and password.
If you have just logged in and received the 401 error message, it means that the credentials you provided were not valid. This means that you do not have an account on the website, or your username or password was incorrect.
403 (Forbidden)
The HTTP status code 403 Forbidden means that access to the page or resource you are trying to access is strictly prohibited.
In other words, the 403 error means that you do not have access to what you are trying to view.
404 (Not Found)
404 Not Found means that the page you are trying to open cannot be found on the server you are looking for. This is the most popular HTTP status code there is.
The 404 error appears when the page cannot be found. If you want to see the 404 page of iGuRu.gr go here.
408 (Request Timeout)
The 408 Request Timeout indicates that your request was sent to the website, but it did not arrive and the time passed. In other words, a 408 error means that connecting to the website took longer than the website's server was willing to wait.
500 (Internal Server Error)
500 Internal Server Error is a very general HTTP status code and means that something went wrong on the server, and the server could not be more specific in identifying the problem.
The 500 Internal Server Error message is the most common “server-side” error you will see.
502 (Bad Gateway)
The HTTP status code, 502 Bad Gateway means that the server received an invalid response from another server it was accessing while trying to load the web page or complete another browser request. In other words, the 502 error is an issue between two different servers on the Internet that are not communicating properly.
503 (Service Unavailable)
503 Service Unavailable means that the website's server is currently unavailable. 503 errors are usually due to temporary overload or some maintenance being done on the server.
504 (Gateway Timeout)
The 504 Gateway Timeout error code in HTTP means that a server did not receive a timely response from another server that it was accessing while trying to load the web page or complete some other browser request.
