No module named 'pydantic_core._pydantic_core' in AWS Lambda though library is installed for fast api based code

AWS lambda deployment of FastAPI gives the following error:

[ERROR] Runtime.ImportModuleError: Unable to import module 'users_crud': No module named 'pydantic_core._pydantic_core'Traceback (most recent call last):

Though the pydantic lib is already installed. I am using version 3.10 which is now supported by AWS.