Opera

If Opera receives a "Not found (404)" response when you go to a Web site, the site may be using the MDN Web server.

The MDN server (as used on webmail.tele2.no and webmail.bellsouth.net) has a bug that is triggered when the latest version of Opera or IE send "text/html" as a part of the "Accept" header.

To work around this, use the Quick Preferences menu (press the F12 key on your keyboard) to change the browser identification to an older browser, such as Netscape 4.

Note: It is obvious that "text/html" should be expected to be a part of the accept header since it is the most commonly accepted file type by browsers.

This bug in the MDN server has evaded detection because IE usually sends only "*/*" in its "Accept" header, stating that it can accept anything. Microsoft's practice here has in effect made the "Accept" header next to worthless in HTTP content negotiations as the most widespread implementation of it gives no information to web servers about what file types are handled client-side.

The MDN server obviously uses two different modes of communication for old and new browsers. The mode used for modern browsers can not handle "Accept: text/html". This bug can only be fixed by the webmaster or the company selling the MDN web server.