Hi Ravi Divate,
Here is an excerpt from a post on blogs.msdn.com
If you receive an error similar to the one below, your <handler> section is probably invalid.
HTTP Error 500.21 - Internal Server Error
Handler "<HANDLER_NAME>" has a bad module "ManagedPipelineHandler" in its module list
You probably have a handler mapping that does not have the correct precondition. IIS is not forgiving in regard to typos, and preconditions are case-sensitive. The text must be preCondition=”integratedMode” orpreCondition=”classicMode”.
: You can find the preCondition attribute in the web.config for the handler registration.
All the best,
the Telerik team