@Pavankumar7 - are you experiencing this issue for existing/imported notebooks, or for brand new notebooks too?

If it's the former, the notebook may be using an old serverless environment version. When Databricks updates the Serverless environment, existing notebooks don't automatically switch to point at the new version - you have to manually or programmatically update it.

In the notebook itself, click Environment (far right hand side of the screen), then look for "Environment version" and switch to a newer version.
I had a similar issue with some imported notebooks. I updated from Serverless Environment version 1 to version 2 and that fixed it. Interestingly, environment version 3 did not work, but environment version 2 did work.