A website I am currently working on is currently responding to requests on http://www.mysite.com/dv with 301, where I would have expected a 404.
My site has no content item named DV, there is nothing in the site that corresponds to "DV", and I can't understand why on earth I am seeing this. I originally found these /DV/ URLs while looking at Google Webmaster Tools.
Then I used Fiddler to analyse the request and found
Response sent 26 bytes of Cookie data:
Set-Cookie: wwwwebsite#lang=DV; path=/
This appears to correspond to the Maldivian language. I did not enable this language, and it does not appear under /system/Languages.
I then noticed I can also navigate to http://www.mysite.com/de-CH which is not an enabled language on my site either, leading me to believe I will get results like this for every non-enabled language.
Is there a way to return 404 for unsupported languages in Sitecore?
Try seeing what your "languageEmbedding" value in the web.config is set to.
It can be set to the following: asNeeded | always | never
I would normally set it to "never" unless you have a site, which is set in multiplate languages, then set it to "always". The default is "asNeeded" which I frankly find kinda silly :)
The issue you are having sounds similar to http://sdn.sitecore.net/Forum/ShowPost.aspx?postid=51681 but I an't find DV in LanguageDefinitions.config. I am also able to replicate your error so I don't think it is environment specific to your implementation. Would suggest you contact Sitecore Support.
I don't believe this is actually related to languages at all. If you were to add any random characters in place of the DV, you'd still get a 302 redirect to a 404. Perhaps without the language cookie though.
You should follow the directions here to turn on server side error page redirects.
http://herskind.co.uk/blog/2012/03/sitecore-404-without-302
