Pages router data requests returning 404 when middleware is used

[serhalp]

On sites that use pages router and have middleware, loading a page using next/link will attempt to load a JSON file, which will return a 404. If there is no middleware then it works fine. This applies even if the middleware does nothing.

Data

The following is parsed automatically by the Next.js repo e2e test report generator.

test: test/e2e/middleware-base-path/test/index.test.ts
reason: Pages router data requests returning 404 when middleware is used
test case: "Middleware base tests router.query must exist when Link clicked page routing"

[mrbalov]

We have reported this problem to the Netlify Team several times already. Looks like it doesn't cause pages to be 404; however, I'm not 100% sure and still gathering the statistics.

As a local solution, we agreed with the team to make some pages fully static where it is possible: to make sure that the page is generated during the build time, and it does not crash due to the 404 issue. But it doesn't work for pages that require ISR, and they are at risk.

Chat GPT suggested checking cache policies for static assets and making sure that static assets are not cached and are always revalidated. Previously, we had problems with indefinitely cached 404 pages that were created on the fly (probably, not related to this 404 issue with the middleware). You can set/update cache policy for static assets in the netlify.toml file, if you host your website on Netlify.

Hopefully, there will be a solution to this problem.