More ClickOnce trouble – solved

Some time ago, during the Beta ages of Whidbey, I posted about trouble with the new ClickOnce technology. Now ClickOnce hit me again...

Having installed the RTM version of VS 2005, I was preparing a ClickOnce demo, and when I tried to install the simple WinForms app from the auto-generated PUBLISH.HTM within Internet Explorer - nothing happened. Nothing. No error message, no log entry.

I checked the HTTP traffic, which showed that the file was actually downloaded, and had the "application/x-ms-application" content type.

I checked the MIME association in Windows Explorer which showed that .application was associated with dfshim.dll.

I checked that dfshim.dll was loaded into the iexplore process.

I checked that I could install the app by launching the .application file from the file system via Windows Explorer.

I was going mad ... until I remembered about Onfolio...

During Whidbey Beta, I was using Onfolio 1.0, and it turned out that, in order to use it properly with a Beta of .NET Framework 2.0 installed, you had to put a iexplore.exe.config file in the IE directory, containing

<supportedRuntime version="v1.1.4322"/>

Well, guess what - that file was still there.

After renaming it, ClickOnce worked like a charm. And since Onfolio is fixed by now, it too does work.

I thought I'd tell you about this in case you come across a similar issue somewhere, some time. If so, look for the IE config file...

Comments (5)
  1. Firefox says:

    If you’re using ClickOnce and Onfolio, here’s an obscure problem you might run into….

  2. Saurabh says:

    Frank I have blogged here ( on the ClickOnce support for Firefox.

    I would be interested in knowing how Onfolio solves this problem. Does this solution work fro both installed and online ClickOnce applications?

    Feel free to contact me through my blog or post a comment there.


  3. FrankPr says:


    what exactly do you mean? Onfolio is just a browser add-in, so IE is doing the actual ClickOnce work. Due to the config file, IE was loading the wrong version of the CLR, so ClickOnce failed. End of story, IMHO.

    Or do I miss here?



  4. Lucas Tam says:

    I had the SAME problem – spent a couple hours trying to figure out why ClickOnce didn’t work… Totally forgot about my custom iexplore.exe.config file.

    Thanks 🙂

  5. Mike Quinlan says:

    <supportedRuntime version="v1.1.4322"/>

    MY’s been a week trying to figure this out.

    Thanks for posting this.

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