I am troubleshooting an intermittent issue regarding revalidation of our pages.

We do our revalidation very much like this, await res.revalidate(slug):
https://nextjs.org/docs/pages/building-your-application/data-fetching/incremental-static-regeneration#using-on-demand-revalidation

When this works, our paths get revalidated and we see getStaticProps getting called.

But quite often, we have failures. In this case, there is a 300 second wait until it times out and throws an error:

2024-08-16T11:45:00.6916767Z TypeError: fetch failed
2024-08-16T11:45:00.6917100Z     at node:internal/deps/undici/undici:13178:13
2024-08-16T11:45:00.6917141Z     at async /app/nextdist/server/chunks/3249.js:95:40 {
2024-08-16T11:45:00.6917174Z   [cause]: HeadersTimeoutError: Headers Timeout Error
2024-08-16T11:45:00.6917253Z       at Timeout.onParserTimeout [as callback] (node:internal/deps/undici/undici:5975:32)
2024-08-16T11:45:00.6917309Z       at Timeout.onTimeout [as _onTimeout] (node:internal/deps/undici/undici:2356:17)
2024-08-16T11:45:00.6917359Z       at listOnTimeout (node:internal/timers:581:17)
2024-08-16T11:45:00.6917462Z       at process.processTimers (node:internal/timers:519:7) {
2024-08-16T11:45:00.6917515Z     code: 'UND_ERR_HEADERS_TIMEOUT'
2024-08-16T11:45:00.6917546Z   }
2024-08-16T11:45:00.6917578Z }

What is significant is that getStaticProps is never even called. We draw this conclusion by have console logs at the top of getStaticProps that we see working generally, but never called in these failing cases.

This is on Next 12.2.4, not hosted on Vercel.