HTTP Error 403.14 - Forbidden The Web server is configured to not list the contents

I came across this error because I had the wrong .NET version (v2.0 instead of v4.0) configured on the web site application pool. I fixed it this way on Windows Server 2008 R2 and IIS 7. I'm pretty sure the instructions apply to Windows Server 2012 and IIS 8 as well:

• Press keys Windows+R to open the Run dialog, type inetmgr and then click OK. This opens the IIS Manager.
• In the left treeview, locate the Sites node and find the Default Web Site node under it (or the name of the site where the error message appears).
• Right-click the node and select Manage web site -> Advanced settings.... Note the name of the value Application pool. Close this dialog.
• In the treeview to the left, locate and select the node Application pools.
• In the list to the right, locate the Application pool with the same name as the one you noted in the web site settings. Right-click it and select Advanced settings...
• Make sure that the .NET Framework version value is v4.0. Click OK.

This doesn't apply if you're running an older site that actually should have .NET v2.0, of course :)

In my case ASP.NET not registered on server. try to execute this in command prompt:

Windows 32bit

%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -ir

Windows 64bit

%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -ir 

Just in case if anyone reached here looking for solution, here is how i resolved it. By mistake I deleted all files from my server ( bin directory ) but when i recopied all files i missed App_global.asax.dll and App_global.asax.compiled files. Because these files were missing IIS was giving me this error

403 - Forbidden: Access is denied.

As soon as i added these files, it started working perfectly fine.