List Of HTTP Client And Server Error Codes, And Their Meanings


Today I changed a lot of stuff around on the website, and I misspelled one of my hyperlinks. I was emailed by one of Techpopper’s visitors today saying they were taken to a 404 error page. Not being computer savvy, they were confused on why this happened. I am making this list today for you to reference to incase you ever come across one of these errors. I will also try to make this basic as this can get real techy, but I want everyone to be able to understand it. If I forget an important one please let me know.


400 – Bad Request

A 400 Bad Request error occurs when the website’s server thinks that the data sent by your web browser was malformed, and the server wasn’t able to understand the data and process it, so it generated a bad request error. It could also mean it was sent with a bad syntax.

401 – Authorization Required

This error occurs when you try to visit a page that requires the url resource to have user authentication. In most cases, this means you have to login with a username or password somewhere to access the page without an error.

402 – Payment Required

This  error is extremely rare, if it’s even used. It may be used in the future, but because of its current rarity there is little to no information available about it. Sorry.

403 – Forbidden

If you receive a 403 error, a request you sent to the website’s server was legal, but the server refuses to respond to it. Most commonly, one receives this error because the website owner decided to make directory browsing illegal. Instead, they want you to use the links they give to you on pages, and not trying to find hidden stuff by yourself.

404 – Not Found

Perhaps the most common and most well known client error, this error occurs when you try to view a page (or directory) that doesn’t exist on the server.

405 – Method Not Allowed

This is kind of hard to explain. Clients have methods that they use to interact with the server. For example the method GET is a method that retrieves information from the server, such as a web page or a url. There are other methods also, such as the method POST which submits data to the server. The 405 method not allowed error occurs when a web server does not allow a certain type of method to be used.

406 – Not Acceptable

To understand why this error occurs, you have to understand that a web browser can specify what data it wants to receive from the web server it is connecting to. If the web server detects that the kind of data the browser wants to receive is not acceptable, it will generate a 406 error. Luckily, most browsers will accept any kind of data, so this error is very rare.

407 – Proxy Authentication Required

This error code is very similar to the 401 error I explained earlier, but when this error occurs it wants authentication from a proxy server as well.

408 – Request Timed Out

This error occurs when the web server thinks it has taken to long to acquire an established connection between your web browser and the web server, so it drops the connection and displays this error.

409 – Conflict

This error occurs when your web browser sends a request that can not be completed because of some type of server conflict.

410 – Gone

This error occurs when you try to visit a web page that is no longer there, permanently. It is effectively a dead link, and the 410 error is generated so it will not be requested again by a client, and will be removed from index by a search engine.

411 – Length Required

Remember in error 406, where I mentioned that web browsers can specify what kind of data they want to receive from a server? Well, servers can expect things too, and this error occurs when the web server thinks that the web browser should include a  content length specification.

412 – Precondition Failed

This error occurs when the web server thinks that the data sent by your web browser specified a precondition, and the server detected was not met.

413 – Request entity Too Large

This error occurs simply when the web server thinks your web browser is sending too much data.

414 – Request URI Too Large

Similar to the 413 error, this error occurs when the web server thinks your web browser is sending data that contains a URL that is too large.

500 – Internal Server Error

This error means that there was some sort of error with the server, but the server can’t specify exactly what the error is, or what it is caused from.

501 – Not Implemented

Remember how in error 405, I mentioned that clients have methods they use to interact with the server? This error occurs when the method the client is requested is not implemented in the server.

503 – Server Unavailable

This error occurs when the server is unavailable due to something like overloading or server maintenance.


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