What is a 4xx Error Code?
4xx error codes indicate a client-side issue – meaning something on the user or requesting device‘s end is causing the problem, not the server itself.
Specifically, 4xx codes mean the website or page cannot be reached, either because the page is unavailable or the initial request contains incorrect syntax or headers.
Some common examples include:
404 Page Not Found: The requested page or endpoint does not exist on the given server. This may be due to a broken link or typo in the URL.
403 Forbidden: The client does not have permission to access the requested resource. This could be an authorization failure or invalid credentials.
400 Bad Request: There is an issue with the request itself – such as incorrect formatting, invalid parameters, or missing required values.
So in summary, 4xx errors generally mean there is a problem with the initial request rather than the website or server. While frustrating for users, they are typically easier for developers to troubleshoot compared to 5xx server issues.
Origins and Troubleshooting Tips
There are a few common causes of 4xx status codes:
- Typos or broken links leading to invalid URL requests
- Missing cookies/headers for restricted resources
- Code bugs outputting flawed requests
- Outdated cached client data resulting in mismatches
Here are some basic troubleshooting steps:
- Double check request syntax, URLs, and headers
- Clear browser cache and retry
- Try alternative access methods like a different device
- Check for temporary outages with tools like Downdetector
While 4xx errors originate on the client-side, that client is not always the end user! Often the "client" is an intermediate server or proxy. Complex modern web architectures can make hunting down the root cause tricky.
Let me know if this helps explain what 4xx errors indicate or if you have any other questions!
