We had some information in our original ClickOnce Troubleshooting doc about how to set content (MIME) types up in Internet Information Server if you didn't have .NET Framework installed. In a nutshell, when you fetch the .application file for a ClickOnce deployment, the server must return a Content-Type of application/x-ms-application. It will do this automatically if NetFX 2.0 is installed on the server. If it isn't, you have to set it manually.

We ripped these instructions out of the docs for the last doc update (called Doc Refresh 1) because (1) not everybody deploys using IIS, (2) not everybody runs the same version of IIS, and (3) we didn't want the docs to grow stale due to version revs of IIS. But, hey - since this is a blog, and I have no duty to maintain old posts, here's the info we ripped out. Most of you probably know how to do this already - this is for those of you new to the world of Microsoft Smart Client/Web programming who need someone to throw them a bone.

Run inetmgr [from the Run menu on your server] and open the Properties page for vroot (or entire server).

Click the HTTP Headers tab.

Click the File Types button in the Mime Map section.

Click New Type to add a new type. In Associated Extension, type application; in Content Type (MIME), type application/x-ms-application.

Restart IIS.

If you're running Apache, follow these instructions instead.