CaptchaAI Proxy Connection Failures: Diagnosis and Fixes

Proxy connection failures are the most common reason CAPTCHA tasks fail. When CaptchaAI cannot reach the target site through your proxy, you get ERROR_PROXY_NOT_AUTHORIZED, ERROR_PROXY_CONNECTION_FAILED, or the task times out silently. This guide walks through every cause and fix.

Symptoms

What you see	Likely cause
`ERROR_PROXY_NOT_AUTHORIZED`	Wrong credentials or proxy format
`ERROR_PROXY_CONNECTION_FAILED`	Proxy server unreachable or down
Task hangs then times out	Proxy is slow or blocking the target site
`ERROR_BAD_PARAMETERS`	Missing `proxytype` or wrong format
Solve works without proxy, fails with	Proxy-specific issue — not an API problem

Step 1: Verify proxy format

CaptchaAI requires this exact format:

proxytype: HTTP | HTTPS | SOCKS4 | SOCKS5
proxy: host:port:username:password

Common mistakes:

# WRONG — full URL format
"proxy": "http://user:pass@host:8080"

# WRONG — missing proxytype
data = {
    "proxy": "192.168.1.1:8080:user:pass"
    # proxytype is missing!
}

# CORRECT
data = {
    "proxytype": "HTTP",
    "proxy": "192.168.1.1:8080:user:pass"
}

For proxies without authentication:

data = {
    "proxytype": "HTTP",
    "proxy": "192.168.1.1:8080"
}

Step 2: Test proxy connectivity

Before sending to CaptchaAI, verify your proxy works directly:

import requests

proxy_host = "192.168.1.1"
proxy_port = "8080"
proxy_user = "user"
proxy_pass = "pass"

proxies = {
    "http": f"http://{proxy_user}:{proxy_pass}@{proxy_host}:{proxy_port}",
    "https": f"http://{proxy_user}:{proxy_pass}@{proxy_host}:{proxy_port}"
}

try:
    resp = requests.get("https://httpbin.org/ip", proxies=proxies, timeout=10)
    print(f"Proxy IP: {resp.json()['origin']}")
    print("Proxy is working")
except requests.exceptions.ProxyError as e:
    print(f"Proxy error: {e}")
except requests.exceptions.ConnectTimeout:
    print("Proxy connection timed out")

If this fails, the proxy itself is the problem — not CaptchaAI.

Step 3: Check proxy type

Mismatching proxy types is a silent failure:

If your proxy is...	Set `proxytype` to...
Standard HTTP proxy	`HTTP`
HTTPS/SSL proxy	`HTTPS`
SOCKS4 proxy	`SOCKS4`
SOCKS5 proxy	`SOCKS5`

If you are unsure, try HTTP first — most residential proxy providers use HTTP.

Step 4: Handle special characters in credentials

Passwords with @, :, #, or % break the proxy string format.

from urllib.parse import quote

password = "p@ss:w0rd#123"
encoded = quote(password, safe="")
# Result: p%40ss%3Aw0rd%23123

data = {
    "proxytype": "HTTP",
    "proxy": f"192.168.1.1:8080:user:{encoded}"
}

Step 5: Check proxy whitelisting

Some proxy providers require IP whitelisting. CaptchaAI solves CAPTCHAs from its own servers, which means your proxy provider must allow connections from CaptchaAI's IP range — not just your local IP.

Fix: Switch to username/password authentication instead of IP whitelisting. Most residential proxy providers support both.

Step 6: Verify proxy is not blocked by the target

Some sites block known proxy IP ranges. Signs:

Solve succeeds but the token is rejected on the target site
Frequent ERROR_CAPTCHA_UNSOLVABLE
Higher failure rate than expected

Fix: Rotate proxies or switch to residential proxies. See the proxy quality guide.

Decision tree

Task fails with proxy error
    ↓
Is proxytype set? → No → Add proxytype parameter
    ↓ Yes
Is format host:port:user:pass? → No → Fix format
    ↓ Yes
Does proxy work directly (httpbin test)? → No → Fix proxy, not CaptchaAI
    ↓ Yes
Special characters in password? → Yes → URL-encode password
    ↓ No
Proxy requires IP whitelisting? → Yes → Switch to username/password auth
    ↓ No
Is proxy type correct (HTTP/SOCKS5)? → No → Change proxytype
    ↓ Yes
Proxy may be blocked by target site → Rotate or switch to residential

FAQ

Do I always need a proxy?

No. Proxies are optional for most CAPTCHA types. They are mandatory for Cloudflare Challenge (cloudflare_challenge method) and recommended for Cloudflare Turnstile.

My proxy works locally but fails on CaptchaAI. Why?

Your proxy likely uses IP whitelisting and only allows connections from your IP. CaptchaAI connects from its own servers. Switch to username/password authentication.