IIS Express 10 (64 bit) errors when starting web project in Visual Studio 2015

Question

Starting a web project in IIS Express 10 and Visual Studio 2015 results in the following error when running the 64 bit version of IIS Express but works fine with the 32 bit version.

Process with an Id of 9172 is not running.

These are the fixes I have tried, all have failed:

1. Rename/Delete the IISExpress folder under my documents.
2. Run Visual Studio as Administrator at all times.
3. Reboot...because turn it off and on again.
4. I checked the _CSRUN_DISABLE_WORKAROUNDS environment variable as indicated here but it was already set.
5. Repair IIS Express 10 in Programs and Features.

There already seems to be a Connect issue registered with Microsoft which is Active but this has been ongoing since VS 2010. I have also done some investigation.

• Running C:\Program Files (x86)\IIS Express\iisexpress.exe, starts fine. This is presumably the 32 bit version.
• Running C:\Program Files\IIS Express\iisexpress.exe (Which I assume is the 64 bit version) results in the following error:

Filename: \?\C:\Windows\Microsoft.NET\Framework64\v4.0.30319\CONFIG\web.config Line number: 519 Error: The configuration section 'microsoft.applicationServer' cannot be read because it is missing a section declaration.

Answer 1

It seems that you have updated C:\Windows\Microsoft.NET\Framework\v4.0.30319\CONFIG\web.config but not updated C:\Windows\Microsoft.NET\Framework64\v4.0.30319\CONFIG\web.config. So, please compare the two files and sync them to solve the problem.

Answer 2

I had a similar problem - the key to solving it was to run iisexpress from the the command line and then look at the error. In my case it said the XML was malformed. I then tried to edit the web.config in XmlNotepad which told me exactly where the bad XML was. In this case - something had put a bad comment in the file - I removed it (IE, fixed the XML issue) and then iisexpress was able to run OK on the command line and in VS 2015.