ngrok tunnel getting expired even before 8 hours

Hi Team,

My ngrok tunnel is getting expired even before its set expiry time. Below is the code which i am using for my postback connection and the error message when i hit the postback url in any browser.

from flask import Flask, request
import os
import datetime
import json
import mysql.connector

app = Flask(__name__)

mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="password123",
database="testdb"
)

my_cursor = mydb.cursor()


def log_name():
# logs will be saved in files with current date
return datetime.datetime.now().strftime("%Y-%m-%d") + '.txt'


@app.route('/post', methods=['POST'])
def post():
# post back json data will be inside request.get_data()
# as an example here it is being stored to a file
f = open(log_name(), 'a+')
order_response = request.get_data()
f.write(str(order_response) + '\n')
structured_response = json.loads(order_response)
print(structured_response)
if structured_response['status'] == "COMPLETE":
print(structured_response['average_price'], structured_response['tradingsymbol'], structured_response['transaction_type'], structured_response['quantity'], structured_response['status'], structured_response['instrument_token'])
# circuit_limits()
print("INSERT INTO order_updates values (\"" + str(structured_response['tradingsymbol']) + "\"," + str(structured_response['instrument_token']) + ",\"" + str(structured_response['status']) + "\",\"" + str(structured_response['transaction_type']) + "\"," + str(structured_response['average_price']) + "," + str(structured_response['quantity']) + ")")
my_cursor.execute("INSERT INTO order_updates values (\"" + str(structured_response['tradingsymbol']) + "\"," + str(structured_response['instrument_token']) + ",\"" + str(structured_response['status']) + "\",\"" + str(structured_response['transaction_type']) + "\"," + str(structured_response['average_price']) + "," + str(structured_response['quantity']) + ")")
mydb.commit()
f.close()
return 'done'


@app.route('/')
def index():
# show the contents of todays log file
if not os.path.exists(log_name()):
open(log_name(), 'a+').close()
return open(log_name()).read()


app.run(debug=True, host='0.0.0.0', port=80)