Requests ProxyError

# the same credentials outside Python: if this works, the URL in your code is the problem
curl -s -o /dev/null -w 'CONNECT %{http_connect}  site %{http_code}\n' \
     -x http://resi.proxymonkey.io:8000 --proxy-user 'USER:PASS' https://example.com/

# the encoded form of a password, ready for a proxy URL
python3 -c 'import sys, urllib.parse; print(urllib.parse.quote(sys.argv[1], safe=""))' 'PASS'

import os
from urllib.parse import quote

import requests

user = os.environ["PM_USER"].strip()
password = quote(os.environ["PM_PASS"].strip(), safe="")
PROXY = f"http://{user}:{password}@resi.proxymonkey.io:8000"

try:
    r = requests.get("https://example.com/", proxies={"http": PROXY, "https": PROXY}, timeout=30)
    print("through the proxy:", r.status_code)
except requests.exceptions.ProxyError as err:
    reason = err.args[0].reason
    inner = getattr(reason, "original_error", reason)
    print(type(inner).__name__, inner)

# NewConnectionError ... Failed to establish a new connection: [Errno 111] Connection refused
# OSError Tunnel connection failed: 407 Proxy Authentication Required
# OSError Tunnel connection failed: 502 Bad Gateway

from scrapy.core.downloader.handlers.http11 import TunnelError
from scrapy.exceptions import (
    CannotResolveHostError,
    DownloadConnectionRefusedError,
    DownloadFailedError,
    DownloadTimeoutError,
)

CAUSES = {
    DownloadConnectionRefusedError: "refused at the proxy address",
    CannotResolveHostError: "a hostname did not resolve",
    TunnelError: "the proxy answered CONNECT with an error",
    DownloadTimeoutError: "no answer in time",
    DownloadFailedError: "the connection failed after it opened",
}

async def start(self):
    for url in self.start_urls:
        yield scrapy.Request(url, errback=self.on_error)

def on_error(self, failure):
    for kind, meaning in CAUSES.items():
        if failure.check(kind):
            self.logger.error("%s: %s", meaning, failure.value)
            return
    self.logger.error("%r", failure.value)

from playwright.sync_api import Error, sync_playwright

PROXY = {"server": "http://resi.proxymonkey.io:8000", "username": "USER", "password": "PASS"}

CAUSES = {
    "ERR_PROXY_CONNECTION_FAILED": "never reached the proxy",
    "ERR_TUNNEL_CONNECTION_FAILED": "the proxy refused CONNECT",
    "ERR_TIMED_OUT": "no answer in time",
}

with sync_playwright() as p:
    browser = p.chromium.launch(proxy=PROXY)
    page = browser.new_page()
    try:
        page.goto("https://example.com/")
    except Error as err:
        cause = next((c for c in CAUSES if c in err.message), None)
        print(CAUSES.get(cause, err.message.splitlines()[0]))
    browser.close()

import { fetch, ProxyAgent } from "undici";

const user = encodeURIComponent(process.env.PM_USER.trim());
const pass = encodeURIComponent(process.env.PM_PASS.trim());
const dispatcher = new ProxyAgent("http://" + user + ":" + pass + "@resi.proxymonkey.io:8000");

try {
  await fetch("https://example.com/", { dispatcher });
} catch (err) {
  const chain = [];
  for (let e = err; e; e = e.cause) chain.push(e.code ?? e.message);
  console.error(chain.join(" <- "));
}

// fetch failed <- ECONNREFUSED