How to resolve "Un-recognized attribute 'targetFramework'. Note that attribute names are case-sensitive." in IIS

While trying to configure a SOAP service in IIS, I came across various issues where I had to do many things to resolve them. One of them is the following issue.

Server Error in '/' Application.
Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: Un-recognized attribute 'targetFramework'. Note that attribute names are case-sensitive.

Source Error:

Line 3: 
Line 4:   
Line 5:     
Line 6:   
Line 7:   

Source File: C:\RestService\RestService2\RestService\web.config    Line: 5

Version Information: Microsoft .NET Framework Version:2.0.50727.5420; ASP.NET Version:2.0.50727.5459

To resolve this issue, what you need to do is, check whether you have installed ASP.NET 4 on your Windows instance.
If it is installed, open up a command window, go to the location where .NET 4 is available,

C:\Users\Administrator>cd C:\Windows\Microsoft.NET\Framework\v4.0.30319

Then run the following command

aspnet_regiis -i

E.g.:- C:\Windows\Microsoft.NET\Framework\v4.0.30319>aspnet_regiis -i

Once this is done, open your IIS (type inetmgr in run) and change your Application pool setting to .Net4 (Go to Application Pools -> click on your project -> Right click and select 'Basic Settings')