Steps to Problem/Issue
- I installed Visual Studio 2012 RTM.
- Created an MVC 4 project template in Visual Studio 2012
- Without any code changes, I hit F5 debug.
- Issue: I get a pop up message “Unable to launch the IIS Express Web Serve“
After much searching and many suggest re-install Visual Studio 2012, but it takes a long time (>20 mins) and I’m pretty stubborn at times to find root cause.
I found myself looking at the applicationhost.config file located at
C:\Users\<username>\Documents\IISExpress\config
Look for <applicationPools> node.
I updated managedRuntimeVersion=”4.0″ to “4.0.30319”
Example:
<applicationPools>
<add name=”Clr4IntegratedAppPool” managedRuntimeVersion=”v4.0.30319″ managedPipelineMode=”Integrated” CLRConfigFile=”%IIS_USER_HOME%\config\aspnet.config” autoStart=”true” />
Back to Visual Studio 2012 Project Solution, I hit F5 Debug and IE loaded with the App!
Roy Kim
Roy Kim on Azure and Microsoft 365 
This worked for me … Thanks Roy Kim
That works!
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the thing is i didnt saw that node. 😦 dont know what to do
Thanks for this, it helped me when I was totally lost.
Just what I needed!
Thanks!
10x, was really helpful
Thanks it worked.
I updated a lot of stuff through Windows Update yesterday, something must have tampered with VS. Worked for me too, thank you so much!
thnk you so much
Hello friends, I want to share with you where I originally indicated in the example and I worked, what I did was uninstall IIS 8 Express, physically remove IIS Express folders in Documents and reinstall IIS again and it worked properly.
That works!
Fantastic advice. Worked with minimal fuss (all other advice seemed to involve multiple convoluted processes!
Thanks Bro You saved my time and life!!!!!!!!!!
very helpful.
changed it per ur instructions then changed it back to v4.0 and it worked fine. hmmmmmmm. hmmmmmm. hmmmmmm. i just love typing hmmmmmmm.
Thanks Bro..
I have tried a lot ways to fix it, and I tried it too, but didn’t work for me. My project is like yours MVC 4 template. Damn it!
Thanks It worked!!!!!!!!!!!!!