Satish Barnala I believe you are seeing this error when you test the bot in webchat and not when you tested the KB from language studio. When you tested the same from language studio we are testing the KB directly. After deployment of KB the bot creation step requires an app service and plan along with the language resource key that you used in language studio. In most probable scenario this language key is incorrectly entered in Azure portal when you hit the create bot button. The key should match the language resource key that is mapped in your language studio and the app service should be up and running after the deployment. If the app service fails to start then you can try a restart of the app service.
Using the Azure portal you need to locate your app service that is used while creating your bot resource and click on the app service that is used and hit the restart option and check if it works.
You could also setup diagnostic logging of your bot service from the Monitoring -> Diagnostic Settings blade of the bot resource and lookup the logs in the selected destination.