Hello karnan sekar,
Most probably you have not upgraded your project correctly. Step 6 from Upgrade Instructions says:
6. Open the folder ~/Sitefinity/ServiceAssemblies
and make sure you delete the assembly there. When you initialize the Newsletters
module, it will be recreated. If you don't do this before you apply the patch, you'll get the following error:
"Unable to load one or more of the requested types. Retrieve the LoaderExceptionsProperty for more information."
the Telerik team