When trying to install a ClickOnce application, I get XML instead of the application installing

I've got a ClickOnce application deployed that many machines can install just fine - except one. That one also happens to be an offsite machine that I don't have direct access to. When the user clicks the "install" button, he gets the XML page instead of the application install开发者_运维问答ing.

I've found that invalid MIME types on the server can cause this, but that's not the case and again: 30 or so machines install it just fine.

I've also found that some browsers won't work with ClickOnce (Firefox: without a plugin, and Google Chrome requires the setup.exe file to be download and started), but the machine in question is using Internet Explorer (though I'm not 100% on the version).

For the time being, I can just point the user to the address and instead of publish.htm, I'll have them use the setup.exe file, but this obviously isn't intuitive for everyday users.

What else could cause this?

This user likely doesn't have the version of the .NET Framework installed that supports ClickOnce. If they do, they likely need to run a repair on their installation... The .NET Framework installs the proper MIME type handlers for Internet Explorer for this and if it's not installed properly you will just get the manifest XML trying to download, rather than the ClickOnce helper launching.

You can have the user go to http://www.smallestdotnet.com, and it will say what version of the framework he/she has and how to upgrade to the latest version.