Website Error Codes Explained: The Ultimate Guide to HTTP Status Codes

What Are HTTP Status Codes?

Every time you visit a webpage, your browser sends a request to a web server asking for that page's content. The server responds with a status code, a three-digit number that tells the browser and you what happened.

Think of it like ordering food at a restaurant. The waiter, or server, might say: "Here's your order" (200 OK), "That dish isn't on the menu anymore" (404), or "Sorry, the kitchen is overwhelmed right now" (503). The status code is the server's way of communicating the outcome.

These codes are defined by the Internet Engineering Task Force (IETF) at ietf.org and form a core part of the HTTP (Hypertext Transfer Protocol) that powers the web.

The Five Categories of HTTP Status Codes

1. 1xx Informational Codes

Informational codes are rarely visible to end users and have no direct SEO impact. You’re unlikely to encounter these as a website owner. They’re mostly relevant to developers working with APIs.

2. 2xx Success Codes

2xx codes confirm the request was received, understood, and completed successfully. As a website owner, you won’t need to troubleshoot these. They’re the green light that everything is working.

2.1 200 OK

The most common status code on the internet. It means everything worked perfectly: the page loaded, the data was returned, and the server is happy. For SEO, a 200 means Google can visit, crawl, and index the page. It's the green light you want on every important page.

3. 3xx Redirection Codes

Redirection codes tell the browser that the content it's looking for has moved elsewhere. How you handle these has significant implications for your SEO.

3.1 301 Moved Permanently

This is the most SEO-important redirect code. A 301 tells Google that a page has permanently moved to a new URL. It passes the majority of the original page's link equity, or ranking power, to the new URL.

Use it when: You've permanently moved or renamed a page, migrated your website, or changed your domain name.

SEO tip: Using 301s properly during a site migration protects your existing Google rankings. If you’re planning a wordpress site migration, getting your redirects right from the start can save you significant ranking recovery time.

3.2 302 Found (Temporary Redirect)

A 302 tells browsers and search engines the page has temporarily moved. Unlike a 301, it does not fully transfer link equity. Google tends to keep the original URL in its index.

Use it when: You've temporarily taken down a page for maintenance or are running a time-limited promotion redirect.

⚠️ Common mistake: Many site owners use 302s when they mean 301s, accidentally weakening their SEO.

3.3 304 Not Modified

This tells the browser: "The page hasn't changed since you last visited, just load your cached version." It speeds up page load times and reduces server load. Not an error, it's efficient behavior.

4. 4xx Client Error Codes

4xx errors mean something went wrong with the request itself, either the page doesn't exist, the user lacks permission, or the request was malformed. These are the most visible errors for everyday internet users.

4.1 400 Bad Request

The server couldn't understand the request due to invalid syntax. This often happens due to corrupted browser cookies, malformed URLs, or oversized request data.

Quick fix for users: Clear your browser cache and cookies, then try again.

4.2 401 Unauthorized

The resource you're trying to access requires valid login credentials, and none were provided or the ones entered were incorrect. You'll often see this on password-protected areas of websites.

Real-world example: Trying to access a members-only area without logging in.

4.3 403 Forbidden

Unlike 401, a 403 means the server knows who you are but is explicitly refusing access. This is often a server permissions issue rather than a login problem.

For website owners: Check your file and directory permissions. Directories should typically be set to 755 and files to 644.

SEO impact: A 403 on important pages blocks both users and search engine crawlers from accessing your content, which can cause ranking drops.

4.4 404 Not Found

The most recognizable error on the internet. A 404 means the server can't find a page at the requested URL. The page either never existed, was deleted, or was moved without a redirect being set up.

For users: Double-check the URL for typos. Try using the site's internal search.

For website owners:

• Set up 301 redirects for deleted or moved pages
• Create a custom, helpful 404 page that guides visitors back to your homepage
• Regularly audit for broken links using Google Search Console or Screaming Frog

SEO impact: Occasional 404s are normal and won't hurt rankings. However, a high volume of 404s signals to Google that your site is poorly maintained, wastes your crawl budget, and can dilute your site's authority, especially if inbound backlinks point to broken URLs.

SEO tip: Use 410, not 404, when you've deliberately deleted a page you don't want indexed. Google removes 410 pages from its index faster than 404s.

4.7 429 Too Many Requests

The user or a bot has sent too many requests in a short time period, and the server is rate-limiting them. Common on APIs and websites with bot protection.

5. 5xx Server Error Codes

5xx errors are never the user’s fault. They indicate problems on the server side. Something is broken or overwhelmed in the infrastructure delivering the website. These require immediate attention from website owners or hosting providers.

Unlike a 404, a 500 error is rarely something a visitor can solve. The issue almost always lies on the server.

5.1 500 Internal Server Error

The catch-all server error. It means something went wrong on the server, but the server doesn't know specifically what. It's the digital equivalent of a "something went wrong" message.

Common causes:

• Plugin or theme conflicts, particularly in WordPress
• Corrupted .htaccess file
• PHP memory limit exceeded
• Incorrect file permissions

How to fix:

1. Refresh the page. Sometimes it's a temporary glitch.
2. Check your server error logs for specific details.
3. In WordPress, deactivate recently installed plugins one by one.
4. Contact your hosting provider if the error persists.

SEO impact: A 500 error prevents Google from crawling and indexing your pages. Persistent 500 errors signal site instability and can lead to ranking drops.

5.2 502 Bad Gateway

This error occurs when one server receives an invalid response from another server it was communicating with. Common with websites that use load balancers, reverse proxies, or CDNs.

Real-world analogy: You call a company's support line, but the agent who answers can't reach the department they're transferring you to, so the call fails.

Quick fix: Refresh the page after a few seconds. If it persists, contact your hosting provider.

5.3 503 Service Unavailable

The server is temporarily unable to handle the request, usually because it's overloaded or undergoing maintenance. Unlike a 500 error, a 503 is often intentional, such as during a planned update window.

SEO tip: If you need to take your site offline for maintenance, configure it to return a 503 with a Retry-After header so search engines know the downtime is temporary and will revisit soon.

SEO impact: Short-term 503s are tolerated by Google. Prolonged 503s, lasting hours or days, can cause your pages to drop in rankings or temporarily disappear from search results.

5.4 504 Gateway Timeout

Similar to 502, but specifically means the upstream server didn't respond in time. Common during traffic spikes or when a backend service is slow to respond.

Quick Reference: 10 Most Common Website Error Codes

How Website Error Codes Affect Your SEO

HTTP status codes are not just technical footnotes. They directly influence how Google crawls, indexes, and ranks your website. If you want to understand how search engines process your site in depth, our guide on how AI is changing search covers how modern crawlers evaluate site health signals.

Which Errors Hurt Rankings Most

1. 404 errors: This error wastes crawl budget and signals a neglected site. High volume means Google spends time on dead ends instead of your real pages.
2. 5xx errors: When Google's crawler encounters a 500 or 503 error, it cannot index the page. If the errors persist for days, Google may drop those pages from search results entirely. Search engines also lose trust in sites with frequent server errors, potentially reducing crawl rates.
3. Incorrect 302: These are fine for temporary moves, but using them permanently means link equity doesn't transfer. Rankings can quietly erode without an obvious cause. Use 301 for any permanent redirect.
4. 403 errors: These errors on important pages block both users and search engine bots, causing content to disappear from search results.

How to Check Your Site for Errors

Here are the most reliable tools to monitor and diagnose your site:

1. Google Search Console: Go to Index > Coverage to see pages returning 4xx and 5xx errors.
2. Screaming Frog: Crawl your site to find all broken links and error codes.
3. Ahrefs or Semrush: Audit tools surface crawl errors with context.
4. Your hosting provider's error logs: The most detailed source for diagnosing 5xx errors.

When to Fix It Yourself vs. When to Call a Developer

Not every error requires a developer. Here's a simple decision guide:

You can handle it yourself if:

• It's a 404 caused by a deleted page. Set up a 301 redirect in your CMS.
• It's a 404 caused by a broken internal link. Edit the link text in your content.
• It's a 302 that should be a 301. Update it in your redirect manager.
• It's a 503 during scheduled maintenance you planned.

Call a developer or your hosting provider if:

• 500 errors persist after refreshing and basic troubleshooting.
• 503 errors aren't related to planned maintenance.
• 403 errors appear on pages that should be publicly accessible.
• Multiple 5xx errors appear across your entire site.
• You're seeing errors after a recent plugin update, server migration, or code change.