How to Read and Fix Common Website Errors (404, 500)
Sooner or later, every website shows an error. A visitor clicks a link and lands on a page that says something has gone wrong, and your first instinct is often a small jolt of panic. The reassuring truth is that most website errors are common, well understood, and fixable, and the cryptic numbers attached to them, like 404 and 500, are actually helpful clues rather than random codes. Once you learn to read them, an error message stops being a mystery and becomes a map to the problem.
This guide explains the website errors you are most likely to meet, what each one is really telling you, why it tends to happen, and the practical steps to put it right. It is written for business owners rather than developers, so the focus is on understanding the cause and knowing your options, including when a fix is straightforward and when it is wiser to call for help.
How status codes work
Every time a browser asks your server for a page, the server replies with a three-digit status code that summarises what happened. These codes are grouped into ranges, and knowing the ranges lets you understand any error at a glance, even one you have never seen before. The first digit tells you the category: the 200s mean success, the 300s mean a redirect, the 400s mean the problem is on the visitor's side of the request, and the 500s mean the problem is on the server's side.
This grouping is the single most useful thing to learn. A 400-range error usually means something about the request was wrong, most often a page that does not exist. A 500-range error means your server tried to handle the request but something broke on its end. That distinction immediately points you toward where the fault lies, which is half the battle when troubleshooting. These same codes also appear in your website logs, a topic covered in our guide on what website logs tell you.
The errors you will meet most
A handful of errors account for the vast majority of what visitors and owners encounter. Learning these few covers most situations you will ever face.
| Code | Meaning and usual cause |
|---|---|
| 404 Not Found | The page does not exist. Usually a moved or deleted page, or a mistyped link. |
| 500 Internal Server Error | The server failed. Often a code, plugin, or configuration fault. |
| 403 Forbidden | Access denied. Often a permissions or security-rule problem. |
| 503 Service Unavailable | Server temporarily overloaded or down for maintenance. |
The 404: page not found
The 404 error is the one almost everyone recognises. It means the visitor asked for a page that the server cannot find. This is a client-side, 400-range error, but the cause is often something on your end: a page was moved or deleted without a redirect, a link was typed wrongly, or an old link elsewhere on the web still points to a page that no longer exists. A stray 404 now and then is harmless, but many of them frustrate visitors and can quietly hurt your search visibility.
Fixing 404s is usually straightforward. If a page moved, set up a redirect from the old address to the new one so anyone following the old link arrives in the right place. If the page is genuinely gone, redirect to the most relevant alternative or a helpful page. It also pays to give your site a friendly custom 404 page that guides lost visitors back to safety rather than leaving them at a dead end. Our dedicated guide on fixing broken links walks through finding and repairing these systematically.
The 500: something broke on the server
A 500 Internal Server Error is more serious because it means the server itself failed while trying to produce the page. It is a generic message, deliberately vague to visitors, which can make it feel alarming. The most common causes are a recent change that introduced a fault, a misbehaving plugin or extension, a corrupted configuration file, or the server running out of resources. Because the visitor sees only a blank failure, the real explanation usually lives in your error logs, which is where troubleshooting should begin.
If a 500 error appears right after you changed something, undoing that change is the fastest first step. If a plugin or extension is the suspect, disabling recent additions one at a time often reveals the culprit. Beyond that, the error log will frequently name the file or function that failed, turning guesswork into a targeted fix. Persistent 500 errors that you cannot trace are a sensible point to involve a developer, since they can indicate deeper configuration or code problems.
The 403 and 503: access and availability
Two other errors round out the common set. A 403 Forbidden means the server understood the request but refuses to fulfil it, usually a permissions issue or a security rule blocking access. It can appear when file permissions are set wrongly or when a protective tool is being overzealous. A 503 Service Unavailable means the server is temporarily unable to respond, often because it is overloaded with traffic or deliberately offline for maintenance. A 503 during a planned update is expected and harmless; a 503 that appears unexpectedly may signal a traffic surge or a struggling server that needs attention.
A calm approach to any error
Whatever the code, a steady process beats panic. First, read the number and place it in its range so you know whether the request or the server is at fault. Second, ask what changed recently, since most sudden errors follow a recent action such as an update, a new plugin, or an edited setting. Third, check your logs, which usually hold the specific detail the visitor's screen hides. Fourth, undo the most recent change if you can, as this resolves a surprising share of problems quickly. This simple sequence handles the majority of errors without specialist help.
Prevention is better still. Many errors trace back to changes made without testing, so make updates carefully, keep a recent backup before significant changes, and watch your logs as part of routine care. These habits sit within the wider rhythm described in our website maintenance guide. If an error coincides with other strange behaviour, it is worth ruling out a compromise using our guide to recovering a hacked website, and because repeated server errors can affect how search engines see your site, our note on technical SEO basics explains why keeping errors low matters for visibility.
Frequently asked questions
What does a 404 error actually mean?+
Is a 500 error dangerous?+
Do 404 errors hurt my search ranking?+
What is the first thing to do when an error appears?+
When should I call a developer?+
References
- Cloudflare Learning Center, HTTP status codes, cloudflare.com/learning
- Google Search Central, HTTP status codes and how Google handles them, developers.google.com/search
Website errors look intimidating but follow predictable patterns. Once you can read the status code and ask what changed, most problems resolve quickly, and good habits prevent many from happening at all. If you would like a partner to monitor and maintain your site so errors are caught early, see our website maintenance services or get in touch.