vercel/next.js · error

Failed to set fetch cache

Error message

Failed to set fetch cache

What it means

In patched fetch's cache-write path, the incrementalCache.set() call (storing the fetched response in the Data Cache) is chained with a .catch that logs this warning instead of throwing; it fires when writing the cache entry fails, and is suppressed when the request was aborted intentionally.

Source

Thrown at packages/next/src/server/lib/patch-fetch.ts:312

        body: bodyBuffer.toString('base64'),
        status: cloned1.status,
        url: cloned1.url,
      }

      serverComponentsHmrCache?.set(cacheKey, fetchedData)

      if (incrementalCacheContext) {
        await incrementalCache.set(
          cacheKey,
          { kind: CachedRouteKind.FETCH, data: fetchedData, revalidate },
          incrementalCacheContext
        )
      }
    })
    .catch((error) => {
      // Don't warn if the request was aborted intentionally.
      if (!signal?.aborted) {
        console.warn(`Failed to set fetch cache`, input, error)
      }
    })
    .finally(handleUnlock)

  const pendingRevalidateKey = `cache-set-${cacheKey}`
  const pendingRevalidates = (workStore.pendingRevalidates ??= {})

  let pendingRevalidatePromise = Promise.resolve()
  if (pendingRevalidateKey in pendingRevalidates) {
    // There is already a pending revalidate entry that we need to await to
    // avoid race conditions.
    pendingRevalidatePromise = pendingRevalidates[pendingRevalidateKey]
  }

  pendingRevalidates[pendingRevalidateKey] = pendingRevalidatePromise
    .then(() => cacheSetPromise)
    .finally(() => {
      // If the pending revalidate is not present in the store, then we have

View on GitHub (pinned to 0eb3775416)

Solutions

1. Check the incremental cache backend for errors (disk, network, permissions); the fetch result was not persisted.

When it happens

Trigger: Thrown at packages/next/src/server/lib/patch-fetch.ts:312 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of vercel/next.js@0eb3775416 (2026-08-19). Data as JSON: /api/errors/afb4bc7edcb1a0c5. Report an issue: GitHub.