ValidationError: 1 validation error for Crew Sequential process error: Agent is missing in the task with the following description

[rithinnandikonda]

ValidationError: 1 validation error for Crew Sequential process error: Agent is missing in the task with the following description

[type=missing_agent_in_task, input_value={'agents': [Agent(role=Se...tial'>, 'verbose': True}, input_type=dict]

https://github.com/crewAIInc/crewAI-examples/tree/main/write_a_book_with_flows

trying to implement a project same like write_a_book_with_flows example,
for reference: https://github.com/crewAIInc/crewAI-examples/blob/main/write_a_book_with_flows/src/write_a_book_with_flows/crews/outline_book_crew/outline_crew.py

CrewBase class with crew method form outline_crew.py is called main.py file's flow class then getting the Validation Error as above agent is missing in the task which is expected to be automatically considered

Need to update version ? currently using crewai ==0.76.9