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An Introduction to Error Codes

It’s not uncommon that during your experience with proxies, you’ll run into a variety of error codes. The good news is that each code indicates a specific issue, meaning troubleshooting is much easier than you think. This guide will cover some of the most common proxy error codes and how to begin resolving them.

What is a Proxy Error?

A proxy error happens when a proxy server encounters a problem processing a client’s request to access a website or resource. These errors, often shown as HTTP codes, can stem from issues with the proxy server, incorrect settings, network disruptions, or the target site itself. Each error type has its own causes and solutions.

There are five types of status codes, each a 3-digit number from 1 to 5. The codes originate from the RFC-9110, the technical specification that defines the standards for HTTP. If you're interested, you can read more about this here. The following are the standard categories of HTTP error codes:

Informational Responses (100-199)

Used to acknowledge that the server has received the request and is processing it. These codes often inform the client during long processes, like a "continue" signal, while awaiting further headers.

Successful Responses (200-299)

Indicates that the request was successful. This includes "200 OK" for standard success and other codes like "201 Created" when new resources are added.

Redirection Messages (300-399)

This signals that additional steps are required, usually for resource relocation. For instance, a "301 Moved Permanently" tells the client to update links for future requests.

Client Error Responses (400-499)

This code indicates issues coming from the client, such as "404 Not Found" for non-existent URLs or "401 Unauthorized" for authentication failures.

Sever Error Responses (500-599)

Reflect errors on the server’s end, like "500 Internal Server Error," which implies a generic issue, or "503 Service Unavailable," meaning the server is overloaded or down for maintenance.

Common Proxy Errors

You might encounter a few proxy-specific errors. These are well-signaled and can be used to debug and move forward quickly with little friction. For example:

404 “Not Found”

A 404 error would indicate that the requested resource isn’t found. This might be that the resource has been moved to another location, deleted, or never existed entirely. If you encounter this error, we’d recommend checking the URL is correct; a single spelling error can cause this and is easily done.

407 “ Proxy Authentication Required”

The 407 error would mean that the proxy credentials were incorrect at the time of request. The proxy server requires authentication, and this error would indicate that the ones supplied in the request were wrong or missing entirely. To troubleshoot this, double-check the username and password of the proxy you’re using.

400 “Bad Request”

Similar to a 407, this error would be seen when the proxy server receives a bad request from the browser. This could be due to invalid syntax, incorrect headers, or unsupported characters. When using a proxy, 400 errors can occur in misconfigured proxy settings or issues with data formatting that the proxy server doesn’t recognise. To resolve, check you’re using the correct configuration, and validating the request format can often resolve this.

408 “Request Timeout”

You may come across this error when a proxy server takes too long to process a request. This delay often results in a timeout error between client and the destination. This can be resolved sometimes by changing provider/proxy; occasionally under extreme load, some providers may experience a slowdown in request speed.

403 “Forbidden”

A 403 error indicates that access to the requested resource is restricted. This often happens when the server acknowledges the request but denies permission, typically due to insufficient privileges or blocked IPs. 403 errors can also occur if directory browsing is disabled on the server, which some users might encounter if trying to access directories without index files.For proxy users, this could mean the proxy IP is blacklisted or lacks authorisation to access specific sites or content. To troubleshoot, verify the permissions associated with the proxies and consider switching IP addresses if your access remains restricted- some blocks may on a proxy level (certain providers will block access to specific sites such as government, payment processors, and financial institutions).

502 “Bad Gateway”

The 502 error appears when a proxy server acting as a gateway or intermediary cannot get a valid response from the upstream server. This could stem from a range of issues, such as server overload, network connectivity problems, or misconfigurations. A 502 error may mean that the proxy server cannot reach the destination server or received an invalid response when using a proxy. Checking the server status or selecting an alternative proxy server can sometimes resolve this issue.

503 “Service Unavailable”

A 503 error signifies that the server is temporarily unable to handle the request, usually due to maintenance or server overload. With a proxy in place, this error can occasionally result from high traffic levels on the proxy server itself, making it unable to route the request. Often, waiting and retrying after some time will resolve the issue, but changing to a less congested proxy provider can also help in cases of consistent 503 errors.

Conclusion

Proxy errors can be frustrating, but understanding these status codes makes troubleshooting straightforward. Each code points to a specific issue, whether it’s a misconfiguration, a connectivity problem, or an access restriction. By checking the error type and following the suggested resolutions, you can often quickly identify and fix the issue, ensuring a smoother and more efficient scraping or automation experience.