If you install IIS after installing framework, you have to register framework in IIS. Otherwise you will get following message after hosting asp.net application in IIS.

ASP.NET 4.5 has not been registered on the Web server. You need to manually configure your Web server for ASP.NET 4.5 in order for your site to run correctly.

You may get error of different version instead of 4.5 according to your configuration. So to register framework in IIS, run the following command in command window.

• Register framework to IIS without changing existing web applications to use this version of ASP.net

C:\windows\Microsoft.NET\Framework\v4.0.30319->aspnet_regiis –ir

• Or Installing framework to IIS

C:\windows\Microsoft.NET\Framework\v4.0.30319->aspnet_regiis –i

This installed ASP.NET version v4.0.30319 without updating all script maps. After installing Rational

System Architect XT, the following command was run:

C:\windows\Microsoft.NET\Framework\v4.0.30319->aspnet_regiis -s W3SVC/1/ROOT/SAXT

This installed ASP.NET version v4.0.30319 at the specified application root and its subfolders. All existing script maps in the specified path and below were updated.

For the Rational System Architect XT Web Service add-on product, the Registration tool was run with the following command:

C:\windows\Microsoft.NET\Framework\v4.0.30319->aspnet_regiis -sW3SVC/1/ROOT/SAXTWebService

Please share, if it is helpful