404 error

What is a 404 error?

A 404 error is a signal from the server that it can't find the page or file you tried to access. It's sent via the HTTP protocol, which governs communication between your browser and the web server. When the address doesn't match an existing resource, the server returns the status code 404 along with an error page. You've probably seen messages such as "404 Not Found" or "Page not found".

In practice, the error occurs when a page has been deleted, moved without a redirect or when the URL is misspelt. It can also happen if an internal link points to an outdated file name or if an element (such as a CSS file or an image) is no longer on the server. Unlike a 200 code, which confirms successful delivery, a 404 means the resource doesn't exist – yet. For search engines, this means that, by default, the page shouldn't be indexed.

How does a 404 error work?

When you enter a web address, your browser sends an HTTP request to the web server. The server then looks for the content at the requested location. If the server can't find it, it responds with HTTP 404. In other words, it's the result of a completely normal process in web communication, just with a negative outcome.

You can compare it to sending a letter to an address where the recipient no longer lives. The letter is returned, and you're told the address doesn't exist – exactly what the browser does with a 404 error.

On most websites, 404 pages are customised with a logo, navigation and perhaps a search function, so the user isn't left without direction. From a digital design perspective, you can use this page to reflect your brand and help the user move on – maybe even with a bit of personality through tone or visual humour, if it suits the brand.

Why do you need to know about 404 errors?

You should know about 404 errors because they affect both user experience and SEO. When a user lands on a dead page, they often get frustrated and leave the site – and that can quickly increase your bounce rate. At the same time, crawlers waste time on pages with no value, which reduces the efficiency of your crawl budget. This means more important pages may not be visited and indexed as often.

Errors that aren't handled can also create duplicate content if pages without content return a 200 status instead of a 404. This is called a "soft 404" and can confuse Google's algorithms. Correct status code handling is therefore part of technical SEO and an important element when you develop a strategy for site optimisation – for both users and search engines.

What types and variants are there?

• Standard 404 – a classic “not found” error, where the server returns status code 404 without further explanation. It can be temporary if the page is simply missing a redirect.
• Soft 404 – the page doesn't exist but incorrectly returns code 200 OK. This makes the crawler think the page is still valid.
• Related status codes – 410 Gone means the page has been permanently removed. 301 and 302 are used for redirects, while 403 means access is denied. When you work with SEO, it's important to choose the right code so search engines understand your signal correctly.

How do you handle 404 errors in practice?

Effective handling starts with regular monitoring. You can use Google Search Console to find errors such as “Submitted URL not found (404)”. Other tools such as Ahrefs, SEMrush or Moz can crawl the site and show broken links. That way, you quickly discover where the problem lies – whether it's internal links, incorrect sitemap URLs or external links pointing to pages that no longer exist.

Once you've identified the errors, you should fix them according to the cause. If a page has been moved, you set up a 301 redirect to the new location. If it has been permanently deleted with no replacement, let it return a 404 or 410. This is where SEO and strategy meet – you need to decide whether the page still has value worth carrying over or whether it can be shut down completely.

You should also review your internal links on an ongoing basis. An editorial workflow for content updates can ensure that old articles don't point to pages that no longer exist. If you work on larger content projects or automated processes in your CMS, good technical collaboration between web development and digital marketing helps prevent these errors from the moment content is published.

A good starting point is these checks:

What should you watch out for?

404 errors may seem harmless, but their combined effect can be significant, especially on large websites. That's why you shouldn't just react when you discover them – you should prevent them. Make sure your CMS generates correct status codes and that redirects don't create loops or send traffic to irrelevant pages.

When working with SEO and content, it's also important to weigh up when to remove pages entirely and when to keep them with updated content. A consistent structure with clear categories and stable URLs reduces the risk of broken links. That way, you improve both the user experience and your website's technical health.