If you try to install the ASP.NET MVC 3 Tools Update announced at MIX11, and you had previously installed (and then uninstalled) the Visual Studio Async CTP or the Visual Studio Async CTP (SP1 Refresh) installed, you might still get this error message:

Blocking Issues:

This product is incompatible with the Microsoft Visual Studio Async CTP. Please uninstall the component, then try to install this product again.

If you do, I have a solution for you!

Simply uninstalling the Async CTP isn’t enough to get past the checks that the MVC 3 Tools Update is looking for.  To get past this issue, you’ll have to go Registry diving and perform some minor surgery.

DISCLAIMER: I am suggesting to you a solution that worked FOR ME, but might not work for you. I am NOT with Microsoft support, and will NOT warranty your system if you do this, or some other crazy thing and brick your computer. This is definitely an instance of “it works on my machine” and your mileage may vary. Use at your own risk. Void where prohibited. Please drink responsibly.

With that out of the way – the operation is actually pretty simple:  start Regedit, navigate to the following registry key and delete it:


Make sure you’re deleting the entire key from the tree view, and not just the parts from the details view.  If you’re nervous about doing this, you can always right-click on the key and export it to your computer before you delete it.

And that’s it!  After the key is gone, re-run the installer and you should be good to go.


Many thanks to Kevin H for using the force to track down this orphaned key for me and helping me get past this annoying blocking issue.

12 thoughts on “Visual Studio Async CTP vs. ASP.NET MVC 3 Tools Refresh

  1. Fixed for me with current release of MVC 3.  I removed both async CTPs and MVC 3 still would not install.  Deleting the reg key fixed it. Thanks!

  2. I couldn’t find that key in my registry under HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionInstallerUserDataS-1-5-18Patches; furthermore I couldn’t find anything that closely resembled Visual Studio Async CTP in my list of installed programs yet I recieved the same error message everybody else did trying to install MVC3

  3. Fixed it. Here’s a solution for anyone who has the problem from my previous post. Attempt to install MVC3 again and when you get to the first dialog request stop. Open up windows explorer and copy the installation folder the installation app just created and rename it. It will have a name that looks like a guid with a creation date of a minute ago. Now cancel the install and run the setup.exe out of this new folder. This program will require your original Visual Studio install disk and repair the issue. Now run the original MVC3 install and you should experience success.

  4. There are moments when you thank 1000 times the existence of the Internat and of guys like you. This IS the one from me!

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