SSG with fallback: true passes empty props while fetching the data

Bug report

Describe the bug

If you specify fallback: true in getStaticPaths, the page is first rendered with {} props, and then rerendered with the result of getStaticProps

Furthermore, hovering over a <Link> pointing to fallback: true page results in a 404 request in the network tab. Even after the page was generated

To Reproduce

Repo: https://github.com/adelnizamutdinov/next-problem

1. git clone [e-mail]:adelnizamutdinov/next-problem.git
2. cd next-problem
3. yarn dev
4. Go to http://localhost:3000 and click the link, you’ll observe the bug of an empty object being passed on every SSG pass
5. yarn build && yarn start
6. Go to http://localhost:3000 and click the link. You’ll observe the bug on first SSG pass. On subsequent visits you’ll visit the already generated page

Expected behavior

First static render is done with the results of getStaticProps, nextjs server should not respond until the data is fetched and the page is generated

Hovering over a <Link> pointing to fallback: true produces a 200 response after the page was generated

System information

• OS: macOS 10.15.4
• Browser Chrome 83
• Version of Next.js: 9.4.4
• Version of Node.js: 14.4.0

[timneutkens]

This behaves as documented: https://nextjs.org/docs/basic-features/data-fetching#fallback-pages

You have to use router.isFallback to check if the page data is ready yet

[feychenie]

Hello, not saying that this solves all the issues, but I can already see that you are not linking to the dynamic route the right way: https://nextjs.org/docs/api-reference/next/link#dynamic-routes