Airflow task_id not found - python-3.x

Question

I am trying to set unique id for each of the celery task in airflow. but for some reason it throws me the following error. I even tried with uuid module and the same error pops up.
Traceback (most recent call last):
File "/home/mahesh/anaconda3/bin/airflow", line 37, in <module>
args.func(args)
File "/home/mahesh/anaconda3/lib/python3.7/site-packages/airflow/utils/cli.py", line 76, in wrapper
return f(*args, **kwargs)
File "/home/mahesh/anaconda3/lib/python3.7/site-packages/airflow/bin/cli.py", line 547, in run
task = dag.get_task(task_id=args.task_id)
File "/home/mahesh/anaconda3/lib/python3.7/site-packages/airflow/models/dag.py", line 1263, in get_task
raise TaskNotFound("Task {task_id} not found".format(task_id=task_id))
airflow.exceptions.TaskNotFound: Task 893370 not found
Following is my DAG
dag_id = 'test'
dag = DAG(dag_id, description='test DAG',
schedule_interval=None, start_date=datetime(2018, 11, 1), catchup=False)
def my_sleeping_function(**context):
url = context['url']
r = requests.head(url)
return {url : r.status_code}
def fetch_final_result(**context):
task_instance = context['task_instance']
ans = []
print("paypal is ", uuid_list)
for i in uuid_list:
data = task_instance.xcom_pull(task_ids=i)
ans.append(data)
print("uber is ", ans)
return ans
run_this_bash_last = PythonOperator(
task_id= 'last',
python_callable=fetch_final_result,
# op_kwargs={'url': 'asd'},
dag=dag,
provide_context=True)
urls = [website1, website2, website3, website4, website5, website6]
for i in urls:
index += 1
ind_id = str(random.randint(1, 100000000000000))
uuid_list.append(ind_id)
task_python = PythonOperator(
# task_id = ind_id,
task_id = ind_id,
python_callable=my_sleeping_function,
op_kwargs={'url': i},
dag=dag,
provide_context=True)
task_python.set_downstream(run_this_bash_last)
Please suggest how to overcome this