vercel/next.js · error

Failed to seed Turbopack cache from ${sourceVersionDir} to $

Error message

Failed to seed Turbopack cache from ${sourceVersionDir} to ${targetVersionDir}.

What it means

seedTurbopackCacheIfNeeded copies a previous Turbopack persistent-cache version directory into the target version via a temp dir plus rename; this warning is logged when seeding fails (missing source, IO error, interrupted copy) and the dev server continues with a cold cache.

Source

Thrown at packages/next/src/lib/turbopack-cache-seed.ts:59

  } catch {
    return
  }
  if (!sourceVersionDir) return

  const tmpDir = `${targetVersionDir}.seeding`
  // Making sure we don't copy partial data if process interrupted
  // There is a potential race condition here
  // if someone wrote to the cache while we were seeding it
  // but with the immutable design and all that, I'm not super worried
  try {
    fs.mkdirSync(cacheDir, { recursive: true })
    fs.rmSync(tmpDir, { recursive: true, force: true })
    seedCacheDir(sourceVersionDir, tmpDir)
    fs.renameSync(tmpDir, targetVersionDir)
    Log.info(`Seeded Turbopack cache from ${sourceVersionDir}.`)
  } catch {
    fs.rmSync(tmpDir, { recursive: true, force: true })
    Log.warn(
      `Failed to seed Turbopack cache from ${sourceVersionDir} to ${targetVersionDir}.`
    )
  }
}

function findSeedSource(
  worktreeInfo: GitWorktreeInfo,
  projectDir: string,
  distDir: string,
  version: string
): string | undefined {
  const projectRelToWorktree = path.relative(
    worktreeInfo.worktreeRoot,
    projectDir
  )
  const distRelToProject = path.relative(projectDir, distDir)
  const currentWorktree = path.resolve(worktreeInfo.worktreeRoot)

View on GitHub (pinned to 0eb3775416)

Solutions

1. Delete the stale .next/cache directory and let Turbopack rebuild its cache.

When it happens

Trigger: Thrown at packages/next/src/lib/turbopack-cache-seed.ts:59 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/d3a1cb5fcd720fe3. Report an issue: GitHub.