Scraping behind a proxy hides your identity and protects your IP from bans, but it doesn’t prevent the proxy servers themselves from being blacklisted. So, simply adopting proxies in your scraping strategy is not enough to guarantee high effectiveness.
That’s why it’s vital to understand when proxy bans happen and how to handle them (spoiler: with automated retries!). In this post, I’ll dig into this subtle problem and show you how to implement automated retry strategies for proxy bans in both Python and JavaScript.
Why Do Proxy Bans Happen?
Proxy bans typically occur when performing a large number of automated requests in a scraping script. Without the proper precautions (which I’ll cover later in this article), the target server may block your requests—even if they come from a rotating proxy IP pool.
Proxy bans usually happen in three main scenarios:
Low-IP-authority proxies: If you're using proxies with low reputation (like datacenter proxies) you’re at risk. These often come from sequential IP blocks (e.g., 198.51.100.10–198.51.100.50), which are easily identifiable by server-side anti-bot systems and may even already be on the blacklist. That’s why it's best to use residential and mobile proxies, as they offer trusted IPs.
Insufficient IP pool: If your proxy network doesn’t provide enough IPs, your scraper will end up reusing the same IPs too frequently, leading to detection and bans.
Bot-like behavior: Even with proxies, if your script doesn't mimic human interaction (e.g., incorrect headers, missing fingerprints, or unnatural interactions), the target site may still detect and ban the proxy IP as a protective measure.
Note that there are also less common scenarios that can lead to proxy IP bans, such as:
Geo-restrictions: Some websites (or even governments) block incoming traffic from specific countries or regions.
Manual bans: Site administrators might manually block IPs they suspect of abusive behavior.
"Bad neighbor" effect: If you're using shared proxies, another user’s actions might get the IP banned—even if you did nothing wrong.
Types of Proxy Bans
Keep in mind, not all proxy bans are the same. These generally fall into three categories:
Soft bans: Temporary blocks that last seconds or minutes, often due to rate-limiting violations.
Hard bans: Permanent bans occur when a proxy IP is blacklisted. Some proxy providers let you request replacement IPs, but repeated hard bans (especially those resulting from violations of what you declared during the KYC (Know Your Customer) process or the provider’s terms and conditions) can lead to full account suspension.
Network-wide bans: Soft or hard bans affecting an entire IP range. These are more common with datacenter proxies (which, as I mentioned earlier, typically come in contiguous IP blocks). If one IP is detected, the whole subnet can get blocked.
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Error Messages and HTTP Status Codes That Indicate Proxy IP Bans
The best way to visualize the various reasons for proxy IP bans is with a summary table.
Note: Some errors can have multiple possible causes, and not every occurrence necessarily means a proxy ban has occurred. However, I’ll still mention them, as you must be aware of these errors to avoid mistakenly interpreting them as proxy IP bans when they are not.
The table of the potential proxy ban errors
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As you’ve learned earlier, it’s not always straightforward to determine whether an error is truly connected to a proxy ban. Sure, it makes sense to spend some time debugging and/or reviewing your scraper’s logs to understand what happened. At the same time, no matter the underlying cause of the error, the best practices for handling it remain the same.
First, remember that reducing the number of requests is a great approach to limit bans. Slowing down your scraping script by limiting consecutive requests or adding longer wait times between individual requests (or batches of them) can greatly lower the risk of your proxies being blocked.
Second, implementing automated retries is often the most effective strategy when dealing with proxy bans. The idea is to detect when a likely proxy-ban-related error occurs, and then retry the request after a delay. That delay is important because it gives the (proxy or site) server time to resolve the issue, assuming the ban isn’t permanent, clearly.
However, retries alone won’t solve the problem if you keep getting the same IP address. That’s why you need to configure your proxy provider for faster IP rotation or ensure they have a sufficiently large pool of IPs. The latter is particularly fundamental in large-scale scraping operations.
Pro tip: A smart retry strategy is to use exponential backoff, where the wait time between retries increases progressively. This approach prevents aggressive retry patterns that could worsen bans or trigger additional blocks.
Randomize your requests: Rotate HTTP headers, such as User-Agent and others. You can also vary HTTP client libraries for getting different TLS fingerprints. The end goal is to make your requests appear less robotic. After all, proxy bans might not always be caused by IP issues.
Monitor and analyze logs: Regularly review your scraper’s logs to identify error patterns. Understanding the frequency and type of bans helps you fine-tune your requesting strategy. That is useful whenrobots.txt files lack clear instructions.
Manage sessions carefully: Avoid using consistent session data, such as identical cookies, across requests coming from different IP addresses. It’s unusual for multiple IPs to share the same session, and doing so can raise suspicion and increase the risk of bans.
Implementing Automatic Retries for Proxy IP Bans
As I explained earlier, the most widely utilized and effective approach to handling proxy bans is retrying requests. In this section, I’ll guide you through how to implement retries using Requests and Axios, the two most popular HTTP clients in Python and JavaScript, respectively.
In both cases, the retry logic involves the following steps:
Making a request to the target site via the configured rotating proxy.
Intercepting and analyzing any errors returned.
If the error matches one of the identified potential proxy ban indicators, wait for a short period before retrying the request.
Note: The implementation below will use a simple constant backoff retry strategy. In production, you should rely on more complex strategies and customize the retry parameters. For more guidance, take a look at my tutorial on implementing exponential backoff for retrying requests.
Let’s dive in!
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Implement a function for constant backoff retry using the Python Requests library as follows:
# pip install requests
import time
import requests
def request_with_constant_backoff(
url,
proxy_url,
max_retries=5,
delay_seconds=2,
):
# For routing the request through a proxy
proxies = {
"http": proxy_url,
"https": proxy_url
}
# Retry the request up to max_retries attempts
for attempt in range(1, max_retries + 1):
try:
# Perform the get request trough the proxy
response = requests.get(url, proxies=proxies)
# Retry if response indicates a potential proxy IP ban
if response.status_code in [401, 403, 407, 429, 502, 503]:
print(f"[Attempt {attempt}] Received HTTP {response.status_code}, retrying in {delay_seconds}s...")
time.sleep(delay_seconds)
continue
# Successful response
return response
except (requests.exceptions.ConnectionError, requests.exceptions.Timeout) as e:
print(f"[Attempt {attempt}] Network error: {e}, retrying in {delay_seconds}s...")
time.sleep(delay_seconds)
continue
print("Max retries reached. Request failed.")
return None
Note: It doesn’t make sense to retry on 407 Proxy Authentication Required errors. These usually mean that something is wrong on the client side (such as incorrect proxy credentials) or that the proxy provider has explicitly blocked your access. In either case, retrying won’t change the outcome of the request.
You can use the above function like this:
response = request_with_constant_backoff(
"https://example.com/", # Replace with your target page
"http://username:password@your-rotating-proxy:port" # Replace with your rotating proxy URL
)
In case of potential proxy bans, this function will retry the request up to five times, applying a constant 2-second delay between attempts.
Remember: This approach only makes sense if you're using rotating residential or mobile proxies. Without proper IP rotation, retries are likely to reuse the same (already banned) IP. That may even make the strategy completely ineffective in cases of permanent hard bans.
Automatic Retries in Axios (JavaScript)
Equivalently, you can achieve the same result in Axios with this function:
// npm install axios https-proxy-agent
const axios = require("axios");
const { HttpsProxyAgent } = require("https-proxy-agent");
// If you are using ESM:
// import axios from "axios";
// import { HttpsProxyAgent } from "https-proxy-agent";
async function requestWithConstantBackoff(url, proxyUrl, maxRetries = 5, delaySeconds = 2) {
// retry the request up to maxRetries times
for (let attempt = 1; attempt <= maxRetries; attempt++) {
try {
// make the request through the proxy URL read from the arguments
const response = await axios.get(url, {
//httpsAgent: new HttpsProxyAgent(proxyUrl),
});
// success scenario
return response;
} catch (error) {
const status = error.response?.status;
// Retry on common proxy ban indicators
if ([401, 403, 429, 502, 503].includes(status) ||
["ECONNRESET", "ECONNREFUSED"].includes(error.code)) {
console.log(`[Attempt ${attempt}] Error ${status || error.code}, retrying in ${delaySeconds}s...`);
// custom sleep logic
await new Promise(resolve => setTimeout(resolve, delaySeconds*1000));
continue;
}
// raise the error in case of a non-proxy-ban-related issue
throw error;
}
}
// default behavior
console.log("Max retries reached. Request failed.");
return null;
}
The solutions I presented above are just basic approaches to handling proxy bans. In real-world scenarios, there are a few key parameters you need to consider when devising your automated retry logic.
Those parameters include:
The type of retry strategy: Exponential backoff, linear backoff, constant backoff, jittered backoff, etc.
The maximum number of retries: Should it be 5, 10, 50, or more?
The maximum delay between retries: A few seconds, tens of seconds, or even several minutes?
The total maximum time to keep retrying: You don’t want your retry logic to run indefinitely due to misconfiguration or persistent failures.
For example, these are some potential realistic combinations of retry settings for proxy ban handling:
Example of real-world retry parameter combinations
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What’s for sure is that these values heavily depend on your specific use case and the target website’s behavior.
On top of that, as you discover optimal parameters (often through trial and error or adaptive learning while scraping) they may need to be adjusted over time. That's because target sites frequently update their anti-bot policies and defenses.
Conclusion
The goal of this post was to explain what proxy bans are, when they happen, and how to handle them. As you’ve seen, the best solution is to automatically retry failed requests—but how many retries, when, and with which tools?
Now you have answers to those questions and know how to implement automated retry logic for proxy ban scenarios in both Python and JavaScript.
I hope you found this technical guide helpful and learned something new today. Feel free to share your thoughts or experiences in the comments—until next time!
