The aspnet_regiis approach described above doesn't appear to work on Windows 8.1:
C:\Windows\system32>aspnet_regiis -i
Microsoft (R) ASP.NET RegIIS version 4.0.30319.33440
Administration utility to install and uninstall ASP.NET on the local machine.
Copyright (C) Microsoft Corporation. All rights reserved.
Start installing ASP.NET (4.0.30319.33440).
This option is not supported on this version of the operating system. Administrators should instead install/uninstall ASP.NET 4.5 with IIS8 using the "Turn Windows Features On/Off" dialog, the Server Manager management tool, or the dism.exe command line tool. For more details please see http://go.microsoft.com/fwlink/?LinkID=216771.
Finished installing ASP.NET (4.0.30319.33440).
I had this problem on Windows 8.1 which wouldn't support the aspnet_regiis -i approach.
Instead you need to go to Control Panel, locate the "Turn Windows features on or off" option and drill down as follows:
Internet Information Services
-> World Wide Web Services
-> Application Development Features
and check the "ASP.NET 4.5" option. In checking this box, other options such as ".NET Extensibility 4.5" and the ISAPI options will be checked automatically.
Apply the changes by clicking OK. Restart your website in IIS and your site should now be accessible.
To resolve 'ASP.NET 4.0 has not been registered. You need to manually configure your Web server for ASP.NET 4.0 in order for your site to run correctly' error when opening a solution we can:
1 Ensure the IIS feature is turned on with ASP.NET. Go to Control Panel\All Control Panel Items\Programs and Features then click 'Turn Windows Featrues on. Then in the IIS --> WWW servers --> App Dev Features ensure that ASP.NET is checked.
The issue occurs after you installed framework 4.5 and/or framework 4.6.
The Visual Studio 2012 Update 5 doesn't fix the issue, I tried that first.
The msdn blog has this to say:
"After the installation of the Microsoft .NET Framework 4.6, users may experience the following dialog box displayed in Microsoft Visual Studio when either creating new Web Site or Windows Azure project or when opening existing projects....."
According to the Blog the dialog is benign. just click OK, nothing is effected by the dialog...
The comments in the blog suggests that VS 2015 has the same problem, maybe even worse.
Visual Studio 2013
Download Visual Studio 2013 Update 4
For more information on the Visual Studio 2013 Update 4, please refer to: Visual Studio 2013 Update 4 KB Article
Visual Studio 2012
An update to address this issue for Microsoft Visual Studio 2012 has been published: KB3002339
To install this update directly from the Microsoft Download Center, here