Do you ever come across a message such as a “404 Not Found” or a “500 Internal Server Error” when you browse the Internet? If you have come across a message like that, then you have come across HTTP error codes. It is a way for the Internet to yell out loud “Hey, folks, we have an issue over here!” The three numbered codes can be quite annoying but they are not just simple errors that websites display when something is wrong.
These error codes are not simple numerical digits, but they are messages informing you of why you cannot view a specific webpage. On this blog, we will explain what HTTP errors are and the reasons behind them, alongside describing the most frequent ones.
What is HTTP error?
HTTP or Hypertext Transfer Protocol is the very core of how web pages interact with your browser. Whenever you use a browser to access various pages on the Internet, your browser generates a request to the host web server. The information request is then followed by the server’s status code, confirming the success of the delivery or otherwise.
HTTP error is a well-defined status code on the web server side whenever there is a problem with your request. If something is wrong – for instance a page couldn’t be found or a server is busy – the server sends back an error code, telling you all is well. These codes can be grouped into categories and each category contains issues of a certain type.
Why does an HTTP error occur?
HTTP errors can occur for various reasons, such as:
- Client-side Issues: Problems originating from the user’s device or browser, like entering an incorrect URL.
- Server-side Issues: Problems with the web server hosting the website, such as downtime or misconfigured settings.
- Network Issues: Connectivity problems between the client and server.
- Human Error: Mistyped URLs or broken links.
- Permission Issues: Restricted access to certain content.
By understanding these errors, you can troubleshoot issues more effectively and know whether the problem is on your end or the website’s.
Common HTTP Codes and Their Meanings
HTTP status/error codes are categorized by their first digit, with each range representing a specific type of issue:
1xx: Informational Responses
These codes indicate that the request was received, and the process is continuing. They’re rarely visible to users.
2xx: Successful Responses
Codes in this range signify that the request was successful. While these aren’t “errors,” they’re worth noting for context:
- 200 OK: The request was successful, and the server delivered the requested resource.
3xx: Redirection Responses
These codes tell the browser to take additional actions to complete the request.
- 301 Moved Permanently: The requested resource has been permanently moved to a new URL.
- 302 Found (Temporary Redirect): The resource has temporarily moved to a different URL.
- 304 Not Modified: Indicates that the cached version of the resource is still valid.
While these aren’t errors in the strictest sense, improper redirects can cause confusion or broken links.
4xx: Client-Side Errors
Errors in this range occur due to issues with the user’s request, such as incorrect URLs or unauthorized access.
400 Bad Request
The server couldn’t understand the request due to malformed syntax. This often happens if the URL is incorrectly typed or the request is corrupted.
Why It Happens:
- Mistyped URLs.
- Corrupted cookies.
- Invalid characters in your request.
Fun Fact: Did you know? Typing too many characters into a URL can also trigger a 400 error. The maximum URL length is roughly 2,048 characters.
401 Unauthorized
This error means you’re trying to access a resource that requires authentication, but you haven’t provided valid credentials.
Why It Happens:
- You’re trying to access restricted content.
- You haven’t logged in, or your session has expired.
Fun Fact: The first-ever password protection system for computers was invented in 1961, and people have been forgetting passwords ever since!
403 Forbidden
Even with proper credentials, you don’t have permission to access the requested resource. This typically occurs when the server blocks access intentionally.
Why It Happens:
- The server is blocking your access.
- Permissions are incorrectly configured.
Fun Fact: Some websites block entire countries using 403 errors for region-specific restrictions—yes, even the internet plays favourites!
404 Not Found
One of the most common errors occurs when the server can’t find the requested resource. It usually means the URL is incorrect or the page has been removed.
Why It Happens:
- The page was deleted or moved.
- You typed the URL wrong.
Fun Fact: Many websites get creative with their 404 pages. For example, Pixar’s 404 page features Sadness from Inside Out saying, “We’re sorry, we couldn’t find your page!”
405 Method Not Allowed
The requested method (e.g., GET, POST) isn’t allowed for the specified resource.
408 Request Timeout
The server didn’t receive a complete request within the allotted time. This often results from slow internet connections.
Why It Happens:
- Slow internet connection.
- Server overload.
Fun Fact: In 2008, Google’s servers temporarily slowed down due to a flood of searches about Michael Jackson’s death.
429 Too Many Requests
This error happens when you’ve exceeded the rate limit for requests, often used as a security measure against bots.
Why It Happens:
- Refreshing a page too often.
- Automated scripts bombarding a server.
Fun Fact: Twitter introduced rate limiting in 2008 after too many users caused their servers to crash during major events.
5xx: Server-Side Errors
These errors indicate a problem with the server processing the request.
500 Internal Server Error
A generic error message when the server encounters an unexpected issue. It could be due to a misconfiguration, software bug, or temporary server overload.
Why It Happens:
- Coding errors on the server.
- Server maintenance or crashes.
Fun Fact: Amazon once lost $66,240 per minute during a brief 500 error outage in 2013. That’s how costly server errors can be!
502 Bad Gateway
This occurs when a server acting as a gateway or proxy receives an invalid response from an upstream server.
Why It Happens:
- Communication issues between servers.
- Temporary glitches.
Fun Fact: Cloudflare, a popular internet infrastructure company, reports that most 502 errors are resolved within minutes, showing how quickly the internet can heal itself.
503 Service Unavailable
The server is temporarily unable to handle the request, often due to maintenance or being overloaded.
Why It Happens:
- Traffic spikes (e.g., viral events).
- Scheduled downtime.
Fun Fact: During Black Friday sales, some major retailers intentionally display 503 errors to limit server strain while keeping their websites live.
504 Gateway Timeout
Similar to a 502 error, this occurs when a server acting as a gateway doesn’t receive a timely response from the upstream server.
Why It Happens:
- Network issues.
- Slow backend servers.
Fun Fact: The first internet “time-out” protocols were established in the 1980s, ensuring systems wouldn’t hang indefinitely.
505 HTTP Version Not Supported
The server doesn’t support the HTTP protocol version used in the request.
How to troubleshoot HTTP Errors
Understanding HTTP error codes is the first step toward troubleshooting them. Here are some tips for addressing common errors:
For 4xx Errors (Client-Side)
- Check the URL: Ensure there are no typos or missing elements.
- Clear Browser Cache and Cookies: Outdated data can cause conflicts.
- Refresh the Page: Sometimes, the error resolves on its own.
- Check Permissions: If you encounter a 401 or 403 error, ensure you have the correct credentials.
For 5xx Errors (Server-Side)
- Retry Later: Server issues are often temporary.
- Contact Website Support: If the problem persists, notify the site administrator.
- Check Server Status: Use tools like DownDetector to verify if the website is down for others.
FAQs About HTTP Error Codes
Q1: Are HTTP errors harmful?
No, HTTP errors are not harmful. They simply indicate communication issues between the browser and the server.
Q2: Can I fix server-side errors?
As a user, you can’t directly fix server-side errors, but you can notify the website’s support team.
Q3: Why do I see 404 errors on certain websites?
404 errors occur when the page you’re trying to access doesn’t exist, either because it was removed or the URL is incorrect.
Conclusion
HTTP status/error codes might seem complicated, but they’re simply tools to help identify issues between your browser and a web server.
By understanding these codes, you can troubleshoot issues more effectively, improve your browsing experience, and even gain insights into web development. Next time you encounter an HTTP error, you’ll know exactly what it means and how to handle it.