EC
ConnectionResetError
PythonERRORNotableConnection ErrorHIGH confidence

Connection reset by peer

Production Risk

Common with long-lived connections; implement reconnect with exponential backoff.

What this means

A subclass of ConnectionError (errno ECONNRESET) raised when the remote peer forcibly resets a TCP connection by sending a RST packet.

Why it happens
  1. 1Remote server crashed or restarted mid-request
  2. 2Firewall or load balancer terminated an idle connection
  3. 3Client sent data after the server closed its write end
How to reproduce

Reading from a socket after the server resets the connection.

trigger — this will error
trigger — this will error
import socket
s = socket.create_connection(('host', 8080))
# Server resets connection
data = s.recv(4096)  # Raises ConnectionResetError

expected output

ConnectionResetError: [Errno 104] Connection reset by peer

Fix

Implement reconnect logic

WHEN After ConnectionResetError

Implement reconnect logic
import socket
import time

def resilient_request(host, port, data, retries=3):
    for attempt in range(retries):
        try:
            with socket.create_connection((host, port), timeout=10) as s:
                s.sendall(data)
                return s.recv(65536)
        except ConnectionResetError:
            if attempt < retries - 1:
                time.sleep(2 ** attempt)  # Exponential backoff
    raise ConnectionResetError("All retries failed")

Why this works

ConnectionResetError is always terminal for that connection; close and reconnect.

Code examples
Triggerpython
import socket
s = socket.create_connection(("host", 8080))
# server resets connection
data = s.recv(4096)  # ConnectionResetError
Handle with try/exceptpython
try:
    data = sock.recv(4096)
except ConnectionResetError:
    sock.close()
    sock = reconnect()
Avoid with reconnect logicpython
import time, socket
for attempt in range(3):
    try:
        with socket.create_connection((host, port)) as s:
            return s.recv(4096)
    except ConnectionResetError:
        time.sleep(2 ** attempt)
What not to do

✕ Retry on the same socket after ConnectionResetError

The connection is permanently broken; create a new socket.

Sources
Official documentation ↗

Python Docs — Built-in Exceptions

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