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Connection timed out during TCP handshake

7 Dec 2025

1 min read

python requests errors

Connection timed out

$ python -c "import requests; requests.get('http://10.255.255.1', timeout=2)"
Traceback (most recent call last):
  ...
requests.exceptions.ConnectTimeout: HTTPConnectionPool(host='10.255.255.1', port=80): Max retries exceeded with url: / (Caused by ConnectTimeoutError(...))

Why this happens

The remote host is unreachable or drops SYN packets; the OS waits until the connection attempt times out.

Fix

  • Verify network reachability (ping, traceroute).
  • Use appropriate timeout and consider retries/backoff.

Wrong code

import requests
# Tiny timeout to an unreachable host
requests.get("http://10.255.255.1", timeout=0.1)

Fixed code

import requests
# Reasonable timeout and retries
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry

session = requests.Session()
session.mount("http://", HTTPAdapter(max_retries=Retry(total=3, backoff_factor=0.5)))
response = session.get("http://example.com", timeout=5)
print(response.status_code)