The path exists in dev but wasn't generated at build time — a missing `generateStaticParams` entry or an ISR revalidation gap.
The path exists in dev but wasn't generated at build time — a missing `generateStaticParams` entry or an ISR revalidation gap.
Add the slug to `generateStaticParams`, enable `dynamicParams: true`, or switch the route to on-demand rendering.
Vercel's Edge Network, serverless function logs, or the deployment dashboard.
Vercel — serverless deployment platform for Next.js and edge apps.
The requested resource could not be found on the server — the page may have been deleted, moved, or the URL was typed incorrectly.
HTTP 404 Not Found is the most recognised error code on the web. It tells the client that the server reached but could not find anything matching the requested URL. A 404 does not mean the server is broken — it simply means the path doesn't map to a resource. A small number of 404s is unavoidable (mistyped URLs, expired campaign links, scraper noise). A large or growing number is a warning sign: deleted pages without redirects, broken internal links, a botched migration, or a CMS misconfiguration.
High SEO impact. 404s waste crawl budget (Googlebot stops crawling broken paths but keeps re-checking them), drop the link equity of inbound backlinks (a backlink to a 404 page gives you nothing), and erode user trust. Google does not penalise sites for having some 404s — it expects them — but it does penalise sites with a high proportion of broken internal links or large numbers of previously-indexed pages now returning 404 without redirects. Sites that migrate without redirects routinely lose 40-80% of organic traffic.
LemWatch crawls your site continuously, catches new 404s the moment they appear, and groups them by source (which page links to the broken URL). It also monitors that pages previously returning 200 don't silently start returning 404 — a classic sign of a botched deploy.