As an experienced web scraper, you know proxies are indispensable for bypassing blocks and scraping undetected. But proxies also come with their fair share of cryptic error codes and connection issues that can grind your scrapers to a halt.
In this comprehensive guide, I‘ll explain the most common proxy error codes, what they mean, and most importantly – how to fix them based on my 5 years of experience using proxies for web scraping.
Contents
What Exactly is a Proxy Error?
First, let‘s quickly cover the basics.
When you send a request through a proxy server to a target website, you‘re relying on two separate servers working together smoothly to fetch the content. The proxy forwards your request, Retrieves the response from the website, and passes it back to you.
Of course, this handoff doesn‘t always go flawlessly. The proxy connection can fail for a number of reasons:
- The proxy IP is blocked or misconfigured
- The target site blocks your scraping attempts
- There are network issues on either server side
- You make too many requests too quickly
When the proxy connection fails, the proxy server returns an HTTP status code indicating what went wrong.
These codes are standardized, so you‘ll see the same common errors across different tools and proxy services. There are 5 main classes of HTTP status codes:
- 1xx Informational – Request is in progress
- 2xx Success – Request succeeded
- 3xx Redirection – Further action required
- 4xx Client Error – Problem with your request
- 5xx Server Error – Problem on the server side
For proxy errors, we mainly care about the 4xx and 5xx codes – the ones telling us something went wrong handling our request.
Learning these common proxy error codes is crucial, because how you fix them depends entirely on the specific problem. Identifying the exact issue from the status code will save you hours of headache and frustration.
Now let‘s dive deeper into the common proxy errors, when you‘ll see them, and most importantly – how to get past them.
4xx Client Errors
These errors indicate there was a problem with the request on your end as the client. Let‘s explore some of the most common 4xx errors when using proxies:
400 Bad Request
The generic 400 Bad Request error means your request was malformed or incomplete in some way. The proxy server or website you‘re scraping can‘t understand or handle it.
Some potential causes:
- Missing headers like User-Agent
- Encoding issues in the request URL
- Sending invalid data in the request body
- Using the wrong HTTP method
I see 400 errors most often when first setting up a scraper – it usually indicates an issue with how I‘m forming the request. They don‘t occur as often once your scraper is mature.
How to Fix It
Carefully inspect your request:
- Double check the URL is encoded properly, especially if it contains query parameters
- Make sure you‘re sending all required headers like User-Agent
- If sending a POST request, verify the data formatting in the request body
- Try stripping down the request to the bare minimum parts needed
Once you identify what exactly is invalid about the request, you can fix it properly and avoid further 400 errors.
403 Forbidden
The 403 error is essentially the website saying "I see what you‘re trying to do, and I‘m not allowing you to do it".
Getting a 403 response means you do not have access to the resource you requested.
There are two main scenarios where you‘ll see 403:
1. 403 from the proxy server
This points to an issue with your proxy service. Potential causes include:
- The proxy IP you‘re using is blacklisted by the site you‘re scraping
- You attempted to access a site that‘s not included in your proxy service plan
- Your IP address is not whitelisted for access on that proxy provider
According to a Proxyrack survey, 403 errors from the proxy are the 2nd most common status code encountered when scraping, occurring in 18% of failed requests.
2. 403 directly from the target website
In this case, the site you‘re scraping is choosing to block you based on:
- Your IP address – they may blacklist entire proxy subnets
- Your location – they may block certain countries/regions
- Your usage patterns – if you look too much like a bot
403 responses directly from the site you‘re scraping are less common, occurring in only 5% of failed requests according to Proxyrack‘s data.
How to Fix 403 Errors
To fix 403 errors:
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For 403 from proxy, switch to a different proxy provider or type of proxies. Residential proxies from major metro areas help avoid blacklists.
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For 403 from the site, rotate your IPs more frequently and use proxies from locations that aren‘t blocked.
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Slow down your requests, randomize patterns, and take other steps to appear more human and avoid bot detection.
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If needed, consult the website‘s robots.txt file to understand their scraping policies.
With trial and error, you can uncover proxy setups that reliably bypass 403 access denied errors from both proxies and sites.
407 Proxy Authentication Required
This one is pretty straightforward – the proxy server needs you to authenticate, and you have not provided valid credentials in your request.
If you‘re using IP whitelisting instead of username/password, you may have neglected to whitelist the specific IP address you‘re connecting from.
According to Proxyrack, 407 errors represent 7% of failed proxy requests.
How to Fix It
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First, double check your username and password are correct if authenticating that way.
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If you‘re using IP whitelisting, make sure to add your current public IP address to the allowed list in your proxy account.
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Try making requests without the proxy entirely to confirm your credentials are working properly.
With valid credentials provided, 407 authentication errors should disappear quickly.
429 Too Many Requests
Ah, the dreaded 429. This error means the site thinks you‘re requesting pages too rapidly, so it has throttled or temporarily blocked you.
429 errors indicate the target site sees your connection as a potential DDoS attack, bot, or web scraper.
You‘ll especially get this when:
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You don‘t rotate IPs, so all requests come from the same IP.
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You don‘t randomize request timing, so the site detects suspiciously rapid automated access.
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You hit the site too heavily in a short period of time.
A Proxyrack survey found 429 errors to be the most common proxy failure, occurring in 20% of blocked requests.
How to Fix 429 Errors
To avoid 429 errors:
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Use rotating, sticky session proxies to constantly change your IP as you scrape.
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Build in randomized delays between requests to vary timing like a human.
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Limit request volume and watch for rate limiting headers from the site.
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Rotate other fingerprint elements like your user agent string.
With good rotation and throttling practices, you can avoid looking like an attacker or bot that‘s hitting the site too aggressively.
5xx Server Errors
This class of error code indicates the proxy server or website is having technical difficulties fulfilling your request. Let‘s look at a few common 5xx errors and fixes:
500 Internal Server Error
A 500 code means the site you requested has suffered some sort of internal exception or issue preventing it from responding properly.
In other words, your request triggered a crash, timeout, or failure on the target server side.
This is not related to your usage of proxies – it just means something unexpected went wrong processing your request on the site‘s end.
According to Proxyrack‘s data, 500 errors account for 13% of failed proxy requests when scraping.
How to Fix It
There‘s often little you can do except wait patiently and try again later once the site recovers.
However, it‘s wise to check whether others are reporting website outages using a tool like Downdetector. That helps confirm the 500 issue is on the server side, not your end.
If the problem keeps occurring, try removing the proxy to isolate whether the issue is between the proxy and website.
502 Bad Gateway
You‘re probably most familiar with 502 errors – they‘re one of the most common proxy failure responses.
A 502 indicates a bad gateway i.e. a faulty communication between:
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Your proxy server and the target website
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Two separate proxy servers in your connection chain
Here are some potential causes:
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The target website is completely down or overloaded. The proxy can‘t complete your request.
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Your backconnect proxy doesn‘t actually have an active pool of IPs to rotate through, so it can‘t connect.
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There‘s a network connectivity issue between the proxies/server.
Bad Gateway 502 errors accounted for 15% of failed proxy requests in Proxyrack‘s data.
How to Fix 502 Errors
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Try accessing the website directly without a proxy. If it‘s down for everyone, you simply need to wait until it‘s back up.
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For 502 errors from a backconnect proxy, switch to a more reliable provider with enough IP addresses.
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Check your internet connectivity to rule out any network issues on your end.
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Consider simplifying your proxy connection chain if possible. The more hops, the more can go wrong.
While 502 errors are common when scraping through proxies, a little troubleshooting usually identifies the weak link.
You‘ll see the 503 status when the site you‘re trying to scrape is temporarily unable to handle requests – usually because it is:
- Down for maintenance or upgrades
- Recovering from a crash or DDoS attack
- Receiving an abnormally high volume of traffic
Essentially, 503 means "The server is overloaded – please try back later!"
According to Proxyrack, 503 errors account for 10% of failed proxy requests during web scraping.
How to Fix It
As with 500 errors, often the only recourse is waiting patiently for the site to recover. However, you should try:
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Accessing the site directly without proxies to confirm the outage is on their end
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Checking the site‘s social media accounts and status sites like Downdetector for updates
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Rotating proxies in case the problem is tied to your current IP
With a little patience, 503 errors usually clear up once traffic levels return to normal.
504 Gateway Timeout
This error indicates that one of the gateways in your proxy connection took too long to complete the request.
It could be either:
- The proxy server didn‘t send a request to the website quickly enough
- The website didn‘t send a response back through the proxy fast enough
Causes for gateway timeout errors include:
- Overloaded proxy or web server
- Network latency between proxy and website
- Bandwidth limits on your proxy service plan
According to Proxyrack, 504 timeouts accounted for 7% of proxy scraping failures.
How to Fix Gateway Timeouts
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First, check your internet speed to make sure the problem isn‘t on your end
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Try repeating the request – timeouts are often transient when servers are busy
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Switch to a less overloaded proxy server or service with more bandwidth
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Optimize your scraper code to better handle timeouts and retries
While timeouts are annoying, a little optimization goes a long way in minimizing their impact.
Best Practices for Avoiding Proxy Errors
Hopefully this gives you a better understanding of common proxy errors, their causes, and steps to resolve them. Here are a few best practices to avoid and handle proxy issues in your scrapers:
Use Residential Proxies
Residential IPs from large proxy networks are harder to detect and block than datacenter IPs. Major proxy providers like BrightData, SmartProxy, and Oxylabs offer reliable residential proxies.
Rotate IPs Frequently
Frequently rotating sticky session proxies helps prevent IP blocks and tackle issues like 403 and 429 errors.
Vary Scraper Patterns
Adding delays, random actions, and rotating elements like user agent makes your scraper appear more human and avoids blocks.
Handle Errors Gracefully
Write scrapers to retry failed requests and automatically cycle through new proxies. This minimizes downtime when you encounter errors.
Monitor Target Sites
Keep an eye on site status using tools like Downdetector to differentiate issues on their end versus your proxies.
Choose Reputable Tools
Using well-supported scraping tools and proxy services means encountering fewer technical issues and better troubleshooting support.
Talk to Your Proxy Provider
If you get an unfamiliar proxy error, don‘t hesitate to reach out to their support team for assistance.
Learning to properly handle proxies errors will make your web scrapers more robust, resilient, and ready for large-scale data extraction.
I hope this guide serves as a solid starting point for troubleshooting proxy connection issues in your own projects. Happy scraping!
