Proxy Errors Explained: 403, 429 & How to Fix Them

Debugging a scraping pipeline is hard enough without cryptic HTTP status codes. If you're seeing errors instead of data, it's time to decode what the server is trying to tell you.

Here are the most common proxy errors and exactly how to resolve them.

1. HTTP 403 Forbidden

The server understands your request but refuses to authorize it.

• The Cause: Your IP has a bad reputation, your headers look like a bot, or you're trying to access a restricted region.
• The Fix: Switch to Elite residential (city + ISP) for hard 403s. A datacenter exit is a common cause — stay on residential.

2. HTTP 429 Too Many Requests

You've hit a rate limit.

• The Cause: You're sending too many requests from the same IP in a short window.
• The Fix: Rotate the IP on every request. If the job needs one identity, a sticky session holds a rotating-pool IP for 1–1440 minutes (default 30).

3. HTTP 407 Proxy Authentication Required

The gateway refused the login. Read the body. Proxy-Authorization required means the header is missing or not Basic. Authentication failed means the username or password did not match. A disabled account uses that same body. There is no IP allowlist on this path. The full breakdown is HTTP 407 from the gateway.

• The Fix: Send Basic credentials. Keep targeting keys on the username. Pass the password raw in a field, and percent-encode it only inside a user:pass@host URL.

A spent bandwidth quota is not a 407. After a successful login the gateway returns 403 with the body Bandwidth quota exceeded.

407 is a missing or rejected login. The body says which. A quota failure is 403.

4. HTTP 502 / 504 Gateway Error

The proxy server is having trouble connecting to the target website.

• The Cause: The target site is down, or the residential peer has disconnected.
• The Fix: Implement retry logic. Residential exits can drop; a retry usually draws a new IP from the rotating pool.

Troubleshooting Flowchart

1. Is it 407? Check credentials.
2. Is it 429? Slow down or increase rotation.
3. Is it 403? Switch to Elite residential.
4. Is it 5xx? Retry the request.

Stop Guessing, Start Scraping

Aethyn's dashboard provides detailed error analytics so you can spot and fix issues before they impact your data delivery.

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