What to do when an “HTTP Error 503. The service is unavailable” error occurs while running Web-related sample browsers

This issue can be resolved by registering ASP.NET in IIS. Follow the below steps to register ASP.NET in IIS:

·      Run aspnet_regiis.exe using the administrator command prompt. Run aspnet_regiis.exe for the highest available framework on your machine.  If you have the 4.0 framework, run the .exe from the following folder:

C:\Windows\Microsoft.NET\Framework\v4.0.21006

·      If you have only the 3.5 framework, run the .exe from the following folder:

C:\Windows\Microsoft.NET\Framework\v2.0.50727

              Please refer the below screen shot.

This will solve the “Service unavailable error” in IIS.