Quick answer
A soft 404 is a URL that appears to be missing but returns a success response such as 200 OK, or redirects to an unhelpful generic page. The response code and the page content disagree, which can confuse users and search systems. NOTABIS currently measures HTTP responses and related crawl evidence; this article explains the concept and a manual check rather than claiming a dedicated soft-404 rule.
What the issue means
A normal 404 or 410 clearly says that the requested resource is unavailable. A soft 404 might show “page not found” text while returning 200, serve an empty template for any unknown path, or redirect every missing URL to the homepage. The browser may look fine, but clients receive a signal that the URL succeeded.
Not every thin or short page is a soft 404. The question is whether the URL is genuinely a useful resource and whether its response matches that purpose.
Why it matters for SEO
Search engines may spend time processing URLs that do not contain the promised content, while users can land on a page that does not answer the link they followed. Consistent response semantics make crawling and reporting clearer. A relevant replacement is usually better served by a direct redirect; a missing page with no replacement should return an honest 404 or 410.
How NOTABIS detects it
NOTABIS records the HTTP status, final URL, response body evidence, and internal links for crawled pages. It can therefore help you find suspicious combinations, such as a page with not-found content or a generic redirect, but the current rule catalogue does not publish a dedicated soft-404 detector. Review the page and response together before drawing a conclusion.
How to check it yourself
- Request an invented path that should not exist.
- Inspect the status, final URL, title, main content, and canonical.
- Search the body for a genuine not-found message and compare it with a real page.
- Test several unknown paths and language or trailing-slash variants.
- Check whether public links or sitemaps point at the suspicious URL.
Use browser tools and curl, including a no-redirect request, so a generic redirect is visible.
How to fix it
Return 404 or 410 for content that is unavailable, with a helpful error page and no misleading success signal. Redirect only when a closely related replacement exists, and update internal links to point directly to it. Fix wildcard routes that render an empty or generic page for arbitrary paths. Re-test known missing paths and valid pages after the change.
When this is intentional or does not need fixing
A search-results page, login flow, or application route may deliberately return 200 even when no item matches, provided that is its documented behaviour and it is not pretending to be a missing content page. Assess the page purpose, template, and indexing controls before changing it.
Related issues
Read HTTP status codes explained, HTTP error responses, 404 Not Found vs 410 Gone, and redirected pages. Google’s crawling-error guidance describes why a successful response can still represent missing content.
Run a NOTABIS audit
Run a NOTABIS SEO audit, inspect response and page evidence for unknown paths, and use the result as a starting point for a manual soft-404 review.