[Python] Bad Request: chat not found, error_code:400, i am have issue while sending message on...

I am working on a project where I want to send all the reminders due in 3 days from now, but I am facing a problem. I have an error code 400 while sending the message on Telegram (for which I am using a Telegram bot)

This is the Code

def send_message(message, id):
url = f"https://api.telegram.org/bot{BOT_TOKEN}/sendMessage"
response = requests.post(url, data={
"chat_id": id,
"text": message,
"parse_mode": "Markdown"
})
print("Telegram Response:", response.text)
return response.status_code

def send_due_reminders():
today = datetime.today().date()

try:
conn, cursor = database_con()

# 1. Check last update date
cursor.execute("SELECT * FROM update_mess WHERE id = %s", ('reminders',))
result = cursor.fetchone()
print(result)

if result:
last_updated = result[2]
telegram_id = int(result[1])
else:
return "No 'reminders' row found in update_mess table."

if last_updated == today:
return "Reminders already sent today."

if not telegram_id:
return "Telegram ID is not set."

# 2. Get due reminders
threshold_date = today + timedelta(days=3)
cursor.execute("""
SELECT id, title, task_detail, due_date, assigned_to
FROM reminders
WHERE status = 'Pending' AND due_date <= %s
""", (threshold_date,))
reminders = cursor.fetchall()

if not reminders:
return "No due reminders within 3 days."

# 3. Format and send message
message = " Upcoming Reminders (Due in 3 Days)\n\n"
for r in reminders:
message += (
f" Title: {r[1]}\n"
f" Task: {r[2]}\n"
f" Assigned To: {r[4]}\n"
f" Due Date: {r[3]}\n\n"
)

print(len(message))

response = send_message(telegram_id, message)

if response == 200:
status = "Reminders were sent to Telegram successfully!"
else:
status = f"Telegram send failed with status code: {response}"

# 4. Update last_updated
cursor.execute("UPDATE update_mess SET last_updated = %s WHERE id = %s", (today, 'reminders'))
conn.commit()

return status

except Exception as err:
return f"Error: {err}"

finally:
cursor.close()
conn.close()


Output

('reminders', '62XXXXXXX', datetime.date(2025, 6, 2))

len of mess:652

Telegram Response: {"ok":false,"error_code":400,"description":"Bad Request: chat not found"}

What I have tried

The telegram ID is working. I have tried the same ID in different parts of the project, where it sends reminder details on completion, updating, and creation of the reminder

I have changed message to plain message so it does not mess with the "Markdown" part of the code "parse_mode": "Markdown"

I have checked if the message is not too long len of mess: 652, and I guess this is not that big (chatGPT told me we can send 4096 characters)

At this point I don't know what is the problem

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