HTTP Error 500.21 - Internal Server Error

Handler "ExtensionlessUrlHandler-Integrated-4.0" has a bad module "ManagedPipelineHandler" in its module list

Most likely causes:

• Managed handler is used; however, ASP.NET is not installed or is not installed completely.
• There is a typographical error in the configuration for the handler module list.

Things you can try:

• Install ASP.NET if you are using managed handler.
• Ensure that the handler module's name is specified correctly. Module names are case-sensitive and use the format modules="StaticFileModule,DefaultDocumentModule,DirectoryListingModule".

Solution:

1.run the command prompt as administrator
2.type the line in the command prompt below any one

%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i
or
%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -i

don't change the directory of cmd

3.At the command prompt, type the following command, and then press Enter:

  iisreset