How can I prevent the "Page not found" error when implementing dynamic

Question

Hey there I’m working with a Next.js app and trying to implement dynamic routing with Static Site Generation (SSG). I’m using a dynamic route such as [slug].js to generate pages based on dynamic data but I’m encountering a Page not found error when trying to access the generated pages. I understand that Next.js uses the getStaticPaths function to determine which dynamic pages should be pre-rendered at build time and getStaticProps for data fetching for each of those pages. However despite following this process I keep running into the Page not found error for some routes. Here’s what I’ve already checked: I have a [slug].js file in the pages folder. I am using getStaticPaths to fetch a list of possible slug values (from a CMS or an API) to generate the pages. I am using getStaticProps to fetch the data for each individual page based on the slug . Even though I’ve set this up some pages are not getting generated and I keep seeing the Page not found error when trying to access them in the browser. How can I ensure that all the dynamic pages are correctly generated to avoid this error? Are there any common issues with getStaticPaths or getStaticProps that I might be overlooking? Things I’m unsure about: How should getStaticPaths be structured to fetch all possible paths properly? What could be causing Next.js to not pre-render certain dynamic pages even though the correct slugs are being returned from getStaticPaths ? I would appreciate any guidance on troubleshooting this issue and ensuring that all dynamic pages are pre-rendered successfully in Next.js.

Amira Bedhiafi · Answer

export async function getStaticPaths() { const slugs = await fetchSlugs(); return { paths: slugs.map((slug) => ({ params: { slug } })) fallback: false }; } Your getStaticPaths should look like above and the getStaticProps correctly fetches data for each slug : export async function getStaticProps({ params }) { const slug = params.slug; const data = await fetchDataForSlug(slug); if (!data) { return { notFound: true }; } return { props: { data } }; }

Tuhin Paul · Answer

I am sharing a tentative flowchart for dynamic routing with Static Site Generation (SSG) please check and let me know if this works for you?

Tuhin Paul · Answer

Another approach is : Validate getStaticProps : Check getStaticProps fetches the correct data for each slug: export async function getStaticProps({ params }) { const data = await fetchDataForSlug(params.slug); // Replace with your data fetching logic if (!data) { return { notFound: true }; // Return a 404 if the slug data doesn't exist } return { props: { data } }; } 404 Pages for Missing Data : If fetchDataForSlug doesn't return data for certain slugs ensure notFound: true is handled in getStaticProps . Verify CMS/API Integration : Ensure the CMS or API provides consistent and accurate data for all expected slugs. Local Testing : Test your application locally using npm run build && npm start to verify that the static pages are being generated.

Tuhin Paul · Answer

Structure of getStaticPaths : Check getStaticPaths is returning the paths correctly. Double-check the params object matches the dynamic route's file name ( [slug].js ). export async function getStaticPaths() { const slugs = await fetchSlugs(); // Replace with your CMS/API logic const paths = slugs.map((slug) => ({ params: { slug } })); return { paths fallback: false }; // Or 'blocking' for fallback rendering } Verify Slugs : Log the slugs and paths in getStaticPaths to ensure all required slugs are fetched and mapped correctly. Check Fallback Setting : If fallback is false  any slug not listed in paths will show a 404 error. Use fallback: true or blocking to handle pages dynamically. Build Logs : During the build process ensure that all expected pages are generated. Look for skipped or missing paths.