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Error 404, etc: what the most common errors mean on Chrome, Firefox and other web browsers

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Error 404, error 401, error 500… Sound familiar? If you regularly browse online, you may have encountered them, since they are the most common errors that appear on Chrome, Firefox, Opera, and other web browsers. To help you out, we’ve made a list of the top errors and explained what they mean.


Before we get started, what’s an HTTP error?

HTTP errors occur when you want to go to a web address and the browser isn’t able to access it, which can happen for different reasons.

The most common types of errors start with the numbers 4 and 5. Although there are error codes that start with 1, 2 and 3, you’re unlikely to encounter them when browsing.

These error numbers are usually followed by a short explanation, but they don’t give you much information. So, we’ll give you the full scoop on each of them below.

What the most common HTTP errors mean

Error HTTP 404 (Not Found)

This error means that the page you want to access doesn’t exist at the moment. This may be because you incorrectly entered the web address or because the page owners deleted it. It’s possible that a page showing a 404 error won’t have one later on, which means it’s come back online.

Error HTTP 403 (Forbidden)

This error shows up when you try to access a prohibited web page, i.e. one that isn’t accessible to the public. For example, a database, a backend code (that programmers work with) or a page exclusively for subscribers.

Error HTTP 401 (Unauthorized)

This one is like the 403 error, but it happens when there’s an authentication failure (for example, on the form to access editing of a website). No page should ever show this error, unless it’s for internal use only and isn’t public-facing (for example, a company’s intranet).

Error HTTP 400 (Bad Request)

This error appears when the page you’re trying to access isn’t able to make sense of your request. This usually happens because of a client error or a web address with an invalid format.


Error HTTP 500 (Internal Server Error)

This refers to an error with the internal server you’re trying to access. It could involve different issues related to that server, such as incorrect configuration or an overflow of requests.

Error HTTP 503 (Service Unavailable)

The server can’t respond to the browser’s request because of too much traffic or maintenance. This is usually fixed after a few minutes, especially in the second case.

Error HTTP 504 (Gateway Timeout)

This error means the wait time to return the web page has run out. This may be due to a server error (for example, it’s gone offline) or because the web page has a code that never finishes executing and produces a loop.

Error HTTP 509 (Bandwidth Limit Exceeded)

This error indicates that the web page you want to access has exceeded its bandwidth. This primarily happens on web pages with a cheap “hosting” service that doesn’t allow large volumes of traffic.

So there you have it! May all your webpages load flawlessly and may you never encounter these numbers. And if you do, feel free to refer back here so you know why you’re disappointed.


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