One interesting thing, which is almost never considered, is the fact that error pages very often will pop up in the original site language. Why? Because the webmaster never thought about it in the first place.
Now, from the user experience point of view, this is not exactly thrilling. Imagine that you are navigating a localized French page, and you get a 404 error (Page not found) in English. The user might not understand English in the first place, and he might not even know what a 404 error is. Will he click the page back to where he was? Will he leave altogether? And what will he think/do with more esoteric error codes, such as 503 (Service not available) error? (A list of HTTP error codes can be found for example in the help for Google webmaster tools.)
The worst possibility is that he came to your site from an external link, and therefore (if he goes back previous page) will never have to opportunity to know your products or services. A potential customer is lost simply because there was not an error handling page that could have sent him in the correct direction.
The fact that a user encounters an error is something that all webmasters should consider, as it impacts the user experience and therefore the possibility to lose clients. Thus, well thought-out sites have special error pages offering assistance such as suggestions on possible pages, a link to the home page or sometimes just a funny message that makes the user forget about the fact that he wanted something that is simply not there.
But just as bad as not having an error page is that when you localize your site you forget to localize your error pages. I remember that I was once browsing the English pages of a very interesting Russian site when I encountered a 404 error page – in Russian. I studied some Russian 25 years ago, but I’ve forgotten it all by now, so I did not understand anything.
If you have made the effort to create error pages, make also an effort to localize these, and make sure that when a localized page is not found, then the localized error page pops up. It is not very difficult. For example, if you create your localized site in a subdirectory, then a simple modification to the .htaccess file will ensure that the localized page pops us in the correct language.
A different way would be to detect the browser locale or user language preferences, and present the localized version, it depends on how you handle localized content. But, as I will explain in different post, this might not be a good idea.
But again, when you localize your error pages, remember for which culture you are writing, do not simply copy the original pages. An error page like the one show above might be funny in many cultures, but would be offensive in others. Error pages merit the same localization effort as other pages in your site, as these will mark the difference when a user ends up seeing them
The user experience depends not only on translating the text, but rather on the fact that the user “sees” the site as if it had been made in his language and culture. A small detail such as that ever the error page is localized might not seem important, but customers appreciate small details, and will trust you more than if you just took care of the superficial varnish.
Keep also the search engines in mind, and make sure that your localized error pages also comply with the acceptable rules for these kinds of pages. For example, Google discourages the use of so-called “soft 404s” because they can be a confusing experience for users and search engines. A recent blog on the Official Google Webmaster Central Blog however indicated a means to correct soft 404s using Google Webmaster Tools.
But look at the localized error pages also as an opportunity: Google acknowledges that it uses the links on error pages, even if though it considers these of less importance, so make sure that those links reinforce your localized site!