Knowledgebase: Web Servers
IIS doesn't serve a file for download
Posted by Wolf on 05 November 2009 11:49 AM

Hi - my clients have complained, and I have confirmed from here, that
certain files on my site can no longer be downloaded from links within my
web pages. The files include those with .zip, .wk4, .123, .pps, and .ppt
extensions. The only non-HTML pages that still download are .xls and .pdf.

Can you explain this and fix it?

> I am not sure when exactly this occurred (I am suspecting it was an MS security update) but here is the answer:
> When you request a file from an IIS 6.0 Web server, and the file has a file name extension that is not a defined MIME type on the Web server, you receive the following error message: HTTP Error 404 - File or directory not found.
> Earlier versions of IIS include a wildcard character MIME mapping, which permits IIS to serve any file regardless of its extension. IIS 6.0 does not include this wildcard character MIME mapping and does not serve any type of extension that is not defined at the MimeMap node in the IIS metabase.
> To define a MIME type for a specific extension, follow these steps:
> 1. Open the IIS Microsoft Management Console (MMC), right-click the local computer name, and then click Properties.
> 2. Click MIME Types.
> 3. Click New.
> 4. In the Extension box, type the file name extension that you want (for example, .pdb).
> 5. In the MIME Type box, type application/octet-stream.
> 6. Apply the new settings. Note that you must restart the World Wide Web Publishing Service or wait for the worker process to recycle for the changes to take effect. In this example, IIS now serves files with the .pdb extension

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