Sometimes when you try to visit web page, you’re met with an HTTP error message. It’s a message from the web server that something went wrong. In some cases it could be a mistake you made, but often it’s the site’s fault.

Each type of error has an HTTP error code dedicated to it. For example, if you try to access a non-existing page on a website, you will be met by the familiar 404 error.

Now, you might wonder, which are the most common HTTP errors that people encounter when they surf the Web? That is the question we’ll answer in this article.

Google to the rescue

Why not let millions of Web users tell us themselves what errors they encounter the most? In an indirect way we can do that via Google.

The basic idea here is that some of the people who encounter errors when they visit websites will want to know more about that error, and will go to the nearest search engine to do so.

In short, Google’s search statistics should in this case be able to give us a pretty good idea of which HTTP errors are most common.

Using Google Insights for Search (a great tool for estimating the “popularity” of search terms) we went through all of the different HTTP error codes that exist, comparing them against each other. When the dust settled from this little shootout, we had the top list you can see here below.

The top 5 errors, according to Google

Here they are, listed and explained in reverse order, the five most common HTTP errors. Drumroll, please…

5. HTTP error 401 (unauthorized)

This error happens when a website visitor tries to access a restricted web page but isn’t authorized to do so, usually because of a failed login attempt.

4. HTTP error 400 (bad request)

This is basically an error message from the web server telling you that the application you are using (e.g. your web browser) accessed it incorrectly or that the request was somehow corrupted on the way.

3. HTTP error 403 (forbidden)

This error is similar to the 401 error, but note the difference between unauthorized and forbidden. In this case no login opportunity was available. This can for example happen if you try to access a (forbidden) directory on a website.

2. HTTP error 404 (not found)

Most people are bound to recognize this one. A 404 error happens when you try to access a resource on a web server (usually a web page) that doesn’t exist. Some reasons for this happening can for example be a broken link, a mistyped URL, or that the webmaster has moved the requested page somewhere else (or deleted it). To counter the ill effect of broken links, some websites set up custom pages for them (and some of those are really cool).

And the most common HTTP error of all is……….

1. HTTP error 500 (internal server error)

The description of this error pretty much says it all. It’s a general-purpose error message for when a web server encounters some form of internal error. For example, the web server could be overloaded and therefore unable to handle requests properly.

Judging by Google’s search statistics, this problem is more than twice as common as 404 errors:

Some additional comments on website errors

We would like to point out that all the error messages above are errors reported by the web server back to the visitor (that is the nature of HTTP errors, they come from the web server you are accessing).

Needless to say, if you can’t access a website at all, for example if its network (or yours) is down, you won’t get an HTTP error back. Your connection attempt will simply time out.

We should add that the results from Google actually match our own data quite well. As you might know, we here at Pingdom monitor websites and servers for a living. When helping customers with problems, we have often come upon the dreaded (and pretty vague) HTTP error 500, “internal server error”.

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