Fixing WRONG_VERSION_NUMBER when you use a proxy

Python requests

import os

import requests

USER = os.environ["PROXY_USER"]
PASS = os.environ["PROXY_PASS"]

# The value is how to reach the PROXY: plain http://, also for https:// targets.
proxy = f"http://{USER}:{PASS}@via.proxies.vision:9000"
proxies = {"http": proxy, "https": proxy}

r = requests.get("https://ipinfo.io/ip", proxies=proxies, timeout=30)
print(r.status_code, r.text.strip())

httpx takes the same URL in one argument: httpx.Client(proxy="http://USER:PASS@via.proxies.vision:9000").

Go

proxyURL, _ := url.Parse("http://USER:PASS@via.proxies.vision:9000") // http, not https
client := &http.Client{
	Transport: &http.Transport{Proxy: http.ProxyURL(proxyURL)},
	Timeout:   20 * time.Second,
}
resp, err := client.Get("https://ipinfo.io/ip")

More on proxies in Go, including SOCKS5 and rotation: Proxy authentication in Go’s net/http.

Node.js

import axios from "axios";
import { HttpsProxyAgent } from "https-proxy-agent";

// "Https" in the class name is about the website. The proxy URL stays http://.
const agent = new HttpsProxyAgent("http://USER:PASS@via.proxies.vision:9000");
const res = await axios.get("https://ipinfo.io/ip", { proxy: false, httpsAgent: agent });

curl

curl -x http://via.proxies.vision:9000 --proxy-user "USER:PASS" https://ipinfo.io/ip

An environment variable sets the proxy

requests, curl and many other tools read HTTPS_PROXY from the environment. If that variable holds an https:// proxy URL, you get this error from code that never mentions a proxy. Check with env | grep -i proxy. The name HTTPS_PROXY means “the proxy for https websites”; its value still starts with http://.

The website’s port doesn’t speak TLS

If the error is a plain SSLError without “Unable to connect to proxy” around it, the proxy worked and the far end is the problem. We got exactly that for an https:// URL pointing at a mail server’s port 25. Check the scheme and port of the URL you’re requesting.

A dropped exit

With residential proxies, a correct setup can still fail now and then with UNEXPECTED_EOF_WHILE_READING: the home connection behind that request went away during the handshake. Again there is no ProxyError around it, and the next request works. Retry those; here is a retry that knows the difference.