How to troubleshot 'timeout' error on Airflow - error-handling

Question

I have a new DAG that performs a 3 task operation, the DAG runs fine but every now and then i'm getting a 'timeout' error massage on the top in red. i have now idea why this is.
Does anybody knows what can be the cause ?
Here is my code (with a few parameters i changed for discretion reasons):
from airflow import DAG
from airflow.operators.mysql_operator import MySqlOperator
from datetime import datetime
from airflow.operators.sensors import NamedHivePartitionSensor
from airflow.hooks.presto_hook import PrestoHook
import sys
import os
import logging
sys.path.append(os.environ['SSSSSS'] + '/WWW/WWWWW')
from utils import sql_to_string, parse_exec_to_time, parse_exec_to_date, NewPrestoOperator
from config import emails
from NotifyOperator import NotifyOperator
########################################################################
# Parameters to be set
default_args = {
'owner': 'etl',
'start_date': datetime(2019, 04, 15, 0, 0),
'depends_on_past': True,
'wait_for_downstream': True,
'email': data_team_emails,
'email_on_failure': True,
'email_on_retry': False
}
dag = DAG(dag_id='g13-new_lead_form_alert',
default_args=default_args,
max_active_runs=1,
schedule_interval='0 * * * *')
def _get_records_pandas(query):
start_time = datetime.now()
logging.log(logging.INFO, "Extract Query={}".format(query))
records = PrestoHook(presto_conn_id='{0}-new'.format(os.environ['YYYYY'])).get_pandas_df(query)
logging.log(logging.INFO, "Extract completed. it took:{}".format(str(datetime.now() - start_time)))
return records
SELECT_ALL_QUERY = 'select title, pageloadid from mysql.{0}.agg_pageloadid_lead_form'.format(os.environ['DDDDDD'])
t0 = NamedHivePartitionSensor(task_id='g13-00-wait_for_partition',
partition_names=['{2}.table/dt={0}/tm={1}/'.format(
'{{ (execution_date + macros.timedelta(minutes=60)).strftime(\'%Y-%m-%d\')}}',
'{{ (execution_date + macros.timedelta(minutes=60)).strftime(\'%H\')}}',
os.environ['XXXXX'])],
metastore_conn_id='RRRRRR',
dag=dag,
soft_fail=True,
pool='sensor_tasks',
retries=5
)
t1 = MySqlOperator(
task_id='g13-01-truncate',
sql='''
truncate table {0}.agg_pageloaduid_lead_form
'''.format(os.environ['LLLLL']),
mysql_conn_id='AAAA',
dag=dag)
t2 = NewPrestoOperator(
task_id="g13-02-insert_new_lead",
sql=sql_to_string("/g13_insert_new_lead.sql").format(
os.environ['YYYYY'],
'{{execution_date.strftime(\'%Y-%m-%d\')}}',
'{{execution_date.strftime(\'%H\')}}',
os.environ['ETL_ENVIRONMENT']),
presto_conn_id='{0}-new'.format(os.environ['XXXXX']),
provide_context=True,
fail_on_zero_rows=False,
retries=5,
retry_delay=60,
pool='presto_tasks',
dag=dag
)
t3 = NotifyOperator(
task_id='g13-03-notification',
channels=['test'],
email_recipients=[],
email_subject='New Lead Alert',
email_template="""abc""",
op_kwargs={
'title': 'New Lead Form',
'response': _get_records_pandas(SELECT_ALL_QUERY)
},
dag=dag
)
t0 >> t1 >> t2 >> t3
Any idea what could be causing this ?