Why Do I Get a 404 or 503 Error? (And How to Fix Them)

Estimated reading time: 3 minutes

If you’ve ever clicked a link and been met with a “404 Not Found” or “503 Service Unavailable” message, you know how frustrating it can be.
For website owners, these errors are more than just an inconvenience — they can damage user trust, increase bounce rates, and hurt SEO.

According to Nomensa, error messages like these disrupt the user journey, break confidence in a site’s reliability, and can leave visitors confused about what to do next.

In this guide, we’ll explain:

• What 404 and 503 errors mean
• Why they happen
• How they affect your website’s performance
• How to fix and prevent them

What Is a 404 Error?

A 404 Not Found error means that the page a user tried to visit doesn’t exist on your site.
It could be because:

• The page was deleted
• The URL was changed without a redirect
• The link was typed incorrectly
• An external site linked to the wrong URL

User experience impact:
Visitors hitting a 404 may think your site is broken and leave immediately — often without trying to find the right page.

SEO impact:
While a few 404s won’t harm rankings, large numbers of broken links can lead to lower search engine trust and reduced crawl efficiency.

What Is a 503 Error?

A 503 Service Unavailable error means your server is temporarily unable to handle the request.
This can happen when:

• Your server is overloaded
• Your website is undergoing maintenance
• There’s a temporary hosting or network outage

User experience impact:
Visitors may think your site is down for good and go to a competitor. Frequent 503 errors can make your site look unreliable.

SEO impact:
If search engines encounter repeated 503 errors, they may temporarily drop your pages from search results until the issue is resolved.

Common Causes of 404 & 503 Errors

For 404 Errors:

1. Deleted or moved pages without redirects
2. Broken internal links in menus, buttons, or content
3. Incorrect URLs shared on social media or other sites

For 503 Errors:

1. Traffic spikes overwhelming the server
2. Server or hosting issues
3. Website maintenance without a proper maintenance page

How to Fix a 404 Error

• Set Up 301 Redirects
  If you move or delete a page, redirect the old URL to the most relevant new page.
• Update Internal Links
  Regularly check and fix broken links in your menus, blog posts, and buttons.
• Use a Custom 404 Page
  Create a friendly 404 page that helps users find what they’re looking for instead of leaving your site.

How to Fix a 503 Error

• Upgrade Hosting Resources
  If traffic spikes cause downtime, consider moving to a better hosting plan or using a CDN.
• Schedule Maintenance Wisely
  Run updates or maintenance during low‑traffic periods and display a clear “Maintenance in Progress” message.
• Monitor Server Health
  Use uptime monitoring tools to get alerts when your site goes down.

Tools to Help You Detect & Fix These Errors

• Google Search Console – Reports crawl errors like 404s.
• Screaming Frog SEO Spider – Finds broken links on your site.
• UptimeRobot – Monitors your site’s uptime and alerts you about 503 errors.

How to Prevent These Errors in the Future

• Use permalinks that don’t change unnecessarily.
• Always set up redirects when removing content.
• Invest in reliable hosting to avoid 503 downtime.
• Test your site regularly across devices and links.

Final Thoughts

404 and 503 errors frustrate users, break trust, and can damage your SEO if left unchecked.
The good news? Most of these issues are easy to detect and fix with the right tools and processes.

By:

• Maintaining your site’s link structure
• Investing in reliable hosting
• Providing clear navigation when errors do occur

…you can keep visitors happy and search engines confident in your site.