The 404 page on a landing page: the mistake that costs the most to ignore

A reader clicks a link shared three months earlier on LinkedIn, or an old blog post pointing to an offer that's since been renamed. They land on a blank page, "404 Not Found", no header, no navigation, not a single word telling them where to go. They close the tab. This isn't a visitor lost for lack of interest in the offer — it's a visitor lost to a detail almost nobody double-checks once a landing page goes live: what happens when the URL doesn't match anything?

What research says about broken links and the memory of an experience

The problem is far from anecdotal. A large-scale measurement study published in 2024 analyzed the external links found on the homepages of 88,000 of the world's most-visited websites (the Majestic Million ranking): 35.2% of them contained at least one broken link (study on Google Scholar). A broken link isn't the exception that only happens to poorly maintained sites — it's a third of the most-visited web ignoring it, and a standalone landing page, often linked from dozens of external sources nobody controls (a guest post, a press mention, a two-year-old social post), is even more exposed to it than a typical site.

What makes the mistake costly isn't just how often it happens — it's when it happens in the journey. The landmark study by Daniel Kahneman, Barbara Fredrickson, Charles Schreiber, and Donald Redelmeier, published in 1993 in Psychological Science under the title "When More Pain Is Preferred to Less: Adding a Better End" (study on Google Scholar), laid the groundwork for what's now known as the peak-end rule: the overall memory of an experience isn't the average of every moment in it — it's built almost entirely around its most intense moment and its very last moment. Applied to a landing page, the lesson is direct: a visitor whose visit ends on a blank page with no way out doesn't remember a good offer spoiled by a technical detail — they remember a site that doesn't work, and that memory dominates their judgment of the whole brand far more than the rest of an otherwise smooth visit.

Why a landing page accumulates more broken links than a typical site

A corporate site rarely restructures itself; a landing page, by contrast, lives at the pace of campaigns. Several sources of broken links pile up that don't exist elsewhere:

• Campaign URLs taken down after the fact — a seasonal offer or a one-off webinar whose page gets unpublished once the event is over, while links to it keep living on in archived emails or social posts still online.
• Slug renames during a redesign — moving from /spring-offer to /templates/local-agency breaks every existing external link if no redirect is set up, including ones the team itself shared months earlier.
• Retired A/B test variants — a losing variant disabled after a test, whose URL stays indexed or shared internally in a results spreadsheet.
• Uncontrolled external backlinks — a comparison site, a directory, or a third-party blog post referencing an old URL without anyone knowing about it or being able to fix it directly.

What a good 404 page must do — and must never do

• Keep the site's header and navigation — the visitor should stay inside the brand's world, never land on a blank page that looks like a generic server error and makes them doubt the site still works.
• Offer two or three concrete destinations, not just a search field that shifts the effort back onto the visitor — a link to the homepage, a link to the catalog or the offer closest to what they were probably looking for.
• Return a real HTTP 404 status, never a silent redirect to the homepage with a 200 status: this practice, known as a "soft 404", misleads both the visitor (who doesn't understand why they aren't on the page they expected) and Google, which can flag it as such in the coverage report — see our guide on a landing page not indexed in Search Console to spot this exact case.
• Never reproduce the homepage's content identically — a 404 that shows exactly the same thing as the homepage, with no mention of the error, is another form of soft 404: the visitor no longer knows whether they landed where they meant to or not.
• Track the 404s visitors actually hit in the site's analytics tool to spot the most frequently broken URLs and set up a targeted 301 redirect, rather than letting the error page absorb that traffic indefinitely — a broken link fixed once benefits every visitor after that.

Setting this up on Next.js (App Router)

With Next.js's App Router, a not-found.tsx file placed at the root of a route segment renders automatically whenever no route matches the requested URL, already carrying the correct HTTP 404 status — no middleware or extra configuration needed. On a bilingual site, this file needs to exist separately inside each language route group (for example app/(fr)/not-found.tsx and app/(en)/en/not-found.tsx): without that, an English-speaking visitor who hits a broken link can end up on a 404 page written entirely in French, breaking language consistency at the worst possible moment. For a dynamic page — a template or demo whose slug comes from the URL — the notFound() function from next/navigation needs to be called explicitly as soon as the requested content doesn't exist, rather than letting the page render with empty data: that's what guarantees the correct HTTP status and triggers the right segment's not-found.tsx file.

Once the page is in place, the technical launch checklist remains the right reference to confirm it's actually served with the correct status code before publishing, alongside the canonical tag or the sitemap.

Common mistakes

• Forgetting the other language's version — a half-translated 404, or one missing from one of the two route groups, sends an international visitor to content they can't read.
• Redirecting automatically to the homepage without explanation — a visitor who doesn't understand why they were moved loses trust faster than a visitor clearly told that a page has disappeared.
• Leaning on humor without offering a way out — a creative 404 that gets a smile but offers no clear link to the catalog or homepage fixes the image problem, not the lost conversion.
• Letting an old campaign URL return a 404 indefinitely — if the URL has a clear successor (a new slug, an equivalent offer), a permanent 301 redirect always beats an error page, including for SEO.
• Never checking the 404s actually encountered — without tracking in the analytics tool, the team discovers broken links by chance rather than from data, months after they started driving traffic away.

A good 404 page won't recover every lost visit, but it turns a hard dead end into a concrete second chance. The 10 LanderKit templates (€89 per template, €229 for the full pack) each ship with their own 404 page already styled to match the template's identity and ready to customize: on the SaaS waitlist template as on Local agency, all it takes is adjusting the fallback links offered to the visitor, with no need to rebuild the page from scratch.