Check your custom 404 page

SiteCurl requests a URL that does not exist on your site and examines the response. It checks whether your server returns a custom error page with your site's branding and navigation, or a generic server default like 'Not Found' or the Nginx/Apache default error page.

A custom 404 page should return a proper 404 HTTP status code while displaying helpful content: your site's header, a search bar, or links to your main sections. SiteCurl checks for both the correct status code and the presence of custom content.

Pages that return a 200 status for missing URLs (known as 'soft 404s') are also flagged. This confuses search engines into indexing error pages as real content.

Every site has visitors who land on pages that do not exist. They follow an old bookmark, click a broken link from another site, or mistype a URL. What they see next determines whether they stay or leave.

A default server error page shows a stark message: 'Not Found' or '404 Error' in plain text on a white background. There is no navigation, no search bar, no link back to the home page. The visitor has nowhere to go except the back button. Most leave the site entirely.

A custom 404 page changes that outcome. It keeps your site's header and navigation visible. It suggests popular pages or a search bar. It tells the visitor, in friendly language, that the page they wanted is not here but other content is available. This turns a dead end into a detour.

The HTTP status code matters separately from the page content. If your 404 page returns a 200 status code, search engines treat it as a real page and may index it. You end up with dozens of indexed 'error' pages cluttering your search presence. The page should look custom but still return a proper 404 status.

A default error page loses every visitor who lands on it. There is nowhere to go, nothing to click, and no reason to stay. Your site's navigation, branding, and content are all invisible on that page.

Custom 404 pages recover a portion of those lost visitors. Studies show that a well-designed 404 page with navigation and a search bar keeps 10 to 20 percent of visitors on the site. That is traffic you were already losing for free.

Search engines treat soft 404s (error pages returning a 200 status) as real content. This wastes your crawl budget and can dilute your site's quality signals. A proper 404 status tells search engines to ignore the page and move on.

Content-heavy sites with frequently changing URLs need custom 404 pages the most. Blogs that delete old posts, news sites that archive content, and wikis that reorganize pages all generate 404 hits from stale external links.

E-commerce sites with seasonal or discontinued products get 404 hits from cached search results and old marketing emails. A custom 404 page can redirect shoppers to similar products or current categories.

Any site that has been through a redesign or URL restructuring will have external links pointing to old URLs. A custom 404 page catches every visitor who follows those links.

Step 1: Create a custom 404 page. Design a page that includes your site's header, navigation, and footer. Add a clear message explaining the page was not found. Include a search bar or links to your most popular sections.

Step 2: Configure your server to use it. In Apache, add ErrorDocument 404 /404.html to your .htaccess file. In Nginx, add error_page 404 /404.html; to your server block. In WordPress, most themes include a 404.php template you can customize. In Shopify, edit the 404.liquid template.

Step 3: Verify the status code. Your custom page must return HTTP 404, not 200. Test with curl -sI https://yoursite.com/this-page-does-not-exist and confirm you see HTTP/1.1 404 in the response.

Step 4: Add helpful content. Include links to your home page, popular pages, and a search bar if your site has one. A 404 page that just says 'not found' with your logo is only slightly better than the server default.

Returning a 200 status on the error page. If your server redirects to a custom page instead of serving it directly, the status code may change to 200. This creates a soft 404 that search engines index as real content. Serve the custom page with a 404 status.

Redirecting all 404s to the home page. This confuses visitors who expect to land on a specific page. It also confuses search engines, which see every missing URL resolving to your home page. Show a real 404 page instead.

Forgetting to style the 404 page. If your 404 page does not match the rest of your site, visitors feel lost. Use the same header, footer, and styling as your regular pages.

After setting up your custom 404 page, visit a URL that does not exist on your site (like /test-404-page-xyz). You should see your custom page with full navigation. Then check the status code with curl -sI https://yoursite.com/test-404-page-xyz and confirm it returns HTTP 404.

Run another SiteCurl scan to confirm the check passes. SiteCurl verifies both the custom content and the correct status code.

Every site gets 404 hits. The question is whether those visitors see a dead end or a detour. A custom 404 page with navigation and helpful links recovers lost visitors. Make sure it returns a proper 404 status code so search engines do not index it as real content.