Unknown File Type Dialog
I had an odd problem lately where Internet Explorer (IE 7 & 8 ) stopped opening RTF documents served up by our website. The RTF files were served up by a CGI, so they did not have a “rtf” extension on the URL. IE would present a dialog saying that it did not know what the file type was “Unknown File Type”. All the other browsers (Firefox, Safari, etc) worked fine.
On further investigation I found the server was responding with a mime-type of “application/rtf” and it seems IE no longer knows what this is and expects a mime-type of “application/msword”. I found 2 solutions.
- The best solution, if you control the server, is to change the mime-type of the documents to “application/msword” ().
- If you can not change the server, then try adding the following registry entry to define the “application/rtf” mime-type
[HKEY_CLASSES_ROOT\MIME\Database\Content Type\application/rtf] "Extension"=".rtf"
